Good napper turned bad napper?

I have a 23 month old in my care since February. When he started here, he was only 19 months old.
When he started coming in February, he would walk in and happily go play in the toy room. He had no interest in group activities and preferred playing independently. Since I didn't have much of a group, it wasn't a big deal to me. I had more time to clean. lol. He never needed a morning nap. I would feed him lunch at 11am, and he would go for a nap by 11:45am.
In April, I noticed that he started being extremely tired soon after drop-offs. I'd let him play a little for a half hour, then he'd go for a nap at 8:30am. I'd wake him up by 9:30am. He easily napped by 12:30pm.
Mid-April, his mom went back on rotating shifts so I only have him full days every second week. The other week, I get him at 1:30pm. I have told his mom several times to drop him off at 12:30pm. I now have another dck that needs to nap at 12:30pm. When he walks in, he is disruptive. This wakes up the other dck and disturbs my 4 year old (who is resting). Still, I managed. He'd get here at 1:30pm and would go straight for a nap.
In May, I noticed that he was extremely tired. He was hard to wake up from his morning naps. I had a whole week of him just sleeping. He would get here in the morning and would go for a nap within a half hour of arrival. He'd sleep the whole morning until lunch time. I couldn't wake him up! He'd stay up until 1:30pm and would go back to sleep for the whole afternoon. I commented on his sleep to his parents. They said that he was giving them a hard time to sleep at night, so now they let him stay up much longer.
Lately, he's been easily going for a morning nap. I wake him up an hr into his nap. He is very unhappy. He is cranky all the time, despite naps. I've tried dropping the morning nap, but he can't seem to go without it (thanks to the late nights and 6am wake up time). He fights the afternoon nap, even if his morning nap is a short one.
I currently have him sleeping in a playpen in the toy room. The room is made very dark, so that he can't see too much of the toys around him. The house is kept quiet. He cries about all the blankets, toys,...etc.. He wants them, he doesn't want them, he wants them, he doesn't want them. He throws everything out of the play pen, flips the mattress and then cries for me to go help him. In my opinion, he is too young to sleep on a mattress. In all honesty, I don't have another place for him to sleep. I am seriously considering getting him to sleep in my oldest son's bed. He never sleeps in his bed anyway. I am not prepared for this little guy to have that amount of freedom. He has become very defiant and will stay up until his body can no longer handle it. He cries at the drop of a hat. He is just very unhappy with everything. He was my dream child in the beginning! I don't see as many smiles anymore. He used to be so sweet. Now he's defiant, cranky, fights me on everything. He throws his food on the floor and refuses to eat. (he was a good eater). He throws tantrums at nap time.
What would you do?
Where should he be sleeping?
Should I change his nap schedule?
Should I just let him be cranky and disruptive all morning and let him crash at 11:30am?
Help! (lol)

Schedule and consistency is obviously an issue. He really doesn't know what to expect when and has learned if he fights it that he wins - parents admitted to this.

That doesn't mean he gets to win at daycare. I would leave him in the playpen but make sure it is a very safe place should he decide to climb out. No toys in bed it is sleep time not play time. I don't even allow a stuffy in bed cause it is dangerous and most have grown up without one as infants so no reason to start it as they get older thinking it will keep them sleeping - it keeps them playing.

Yes they almost all go through a stage around 18m where they flip the mattress - usually by then the velcro tabs that hold the mattress down are useless so it is easy to do. Just put the mattress back in place and lay child down, give them a light sheet/blanket either saying nothing as you do it or just repeating it is naptime, lay down and go to sleep. No other interaction. Will waste 1-2 weeks of your quiet time but after that it usually begins to settle down.

On the arrival time there is no reason for child not to arrive at the time you want so state what time he needs to be in care by. I do not allow a child to arrive after lunch because it doesn't give me the freedom I need to put cranky kids down for naps early. I want them to come so there is half hour of playtime then lunch then nap so they are in our normal routine. With their poor sense of time, a half hour of playtime is sufficient.

There may be no other option for a the off weeks but to let him sleep all morning and be up in the afternoon which is probably what mom is doing.

He sounds like an exhausted and confused little 2 year old. :( Poor guy.
I would actually start by insisting that the 1:30 drop offs cease. Smack dab in the middle of naptime, or for that matter anytime after nap begins, would NOT work. And if its an issue of her not wanting to pay for that hour, I would actually offer it without charging, in order to facilitate our scheduling. But it wouldn't be negotiable.
I agree that the only way to enforce that naptime needs to be a specific way is to give up about a weeks worth of your own down time. As playfelt suggested, just keep going in, laying him back down again, and getting him to settle. I wouldn't leave any toys or stuffies, etc. Just his blankets. If he's climbing out, but you feel that he should still be in the playpen, then place him back in and use your stern voice. "NO climbing. It's naptime." Then walk away and watch him. As soon as he gets up, go lay him down again. It's an arduous process, but so very worth it.
As for the overall problem of him having no definable schedule and a bad sleep pattern; it depends on how far you are willing to take it with his mom/dad. I would let them know that you feel like the constantly changing schedule is, indeed, impacting him negatively. Ask if they would be open to working together to develop some consistency. Beyond that, you can't make them do it. If they aren't willing to work on it, you need to decide if you can continue as is, or if you're willing to work on it solo.

Thank you, ladies!
I have offered for them to drop him off at 12:30 with no additional fees. I've told them that he disrupted the others at the 1:30pm drop-off time. I've also told them that I had to start keeping the little girl awake until he arrived and that she is exhausted by that time. (Poor girl).
I have figured things out. It seems that he doesn't like to share a room while sleeping. He was here alone on Tuesday, and napped without any problems in the afternoon. This week, he has been here full days. That probably makes a big difference too. He's also been waking up a little bit easier after the 1 hr nap I allow in the morning. I have him up by 10am. I aim for 9:30, but he doesn't always wake up very easily. At 10am, I pick him up and force him to stand on his feet.
I've also decided that I have a nap schedule. There are no exceptions during nap time. BUT If he is tired before nap time, he can go to sleep earlier, but he has to stay in there until my scheduled nap time is over. (He has been sleeping longer).
I've found in the last couple of days that he sometimes needs a morning nap, and sometimes doesn't. He definitely needs quiet time in a dark room though. Every morning at 8:30am, I change his diaper, wash his hands and put him in the playpen for a nap. Sometimes he sings to himself quietly, sometimes he falls asleep right away. He does not fight me on naps in the morning. When I go in at 9:30, he'll sometimes be passed out, and sometimes jump up excitedly to be taken out for a snack.
No matter what time he woke up from his nap, I still get him to eat lunch at 11:30am. By 12:30pm, he understands that it is nap time. I allow a little bit of play time before 12:30pm, if it does not take him the whole hour to eat. At 12:30pm, I double check his diaper (usually change it right after eating) and place him in the playpen. If he's slept in the morning, he'll protest. Eventually, he'll stop complaining and will sing to himself. By 1:30pm, he is usually asleep.
I never knew playpens had those velcro strips. I never tied them. I guess I never really paid attention to it. I found them on Wednesday after the millionth time of him taking off the mattress. I stuck the strips together, and he hasn't taken the mattress off since. He hasn't even pulled the sheet off.
My other dck hasn't reallly been here much this week, other than Monday and for a brief period yesterday. He seemed to be more upset when she was here during nap time. I've started training them to sleep in the same room. The other dck actually sleeps better in the room with the 23 month old. The 23 month old seems to be getting used to her, but seems to give me the hardest time when she is here.

As far as the parents are concerned.... I am a bit timid when it comes to making suggestions on how to raise their child. I have no problem telling them certain things. Lately, I've been repeatedly telling them what kind of day he has had. Hopefully, this will be a hint that something needs to be changed. I tell them that he is tired, cries a lot, rubs his eyes, sleeps way more than he used to. He is only happy for the first half hour after arrival. Dad's response was that he is always cranky when he wakes up. I replied: I agree that he is cranky when he wakes up, usually only for 5 minutes. After that 5 minutes, he usually wants to join in on the fun and play with all the other kids. Now when he wakes up, he just wants to lay on the couch. When he does get off the couch, he cries or screams about everything. I usually end up putting him back to bed.

I also told them yesterday that they need to send him with better diapers as they should not leak after only having them on for an hr. Yesterday, I changed two pair of clothes because of pee!! Last week, he ended up gettign pee all over the playpen mattress. No sponging worked. I had to put it in the tub and squish all the pee out in the water. I had to lather it in soap and rinse many times. It took the whole weekend to dry and was barely dry on Monday. I put a mattress pad under the sheet, but it doesn't do any good if he rips the sheet off.

So this is what I have decided, since I have trouble talking to his parents about making changes:
-They are aware that he is tired all day here and doesn't want to take part in the activities.
-I have decided that if I plan an activity outdoors, he will come out too. If he is too tired, I will strap him in a stroller and recline the seat so that he can rest, or have him sit on a chair.
- My nap/eating times are going to be consistent, despite the schedule they have him on at home
- If he naps all morning because I have trouble waking him up, he still has to go back for a nap at 12:30pm with the others. If I have to give him a book or a quiet toy to play with for an hr to allow the others to fall asleep, I will. After that hour, I will remove the object.
- If all the other children are awake after my scheduled quiet time (2:30pm), we open the toy room door. I push his play pen to the wall (all while he is still sleeping) and allow them to go in and out as they please to get toys. To be nice (lol), I get them to play out in the living room. I keep the toy room door open though and he is exposed to all the noises in the house, including loud playing.
- I get him up 20 minutes ( at the latest) before his parents pick him up. If he does not wake up, I change his diaper while he is still sleeping, put his shoes on, gather his things and wait for mom or dad to take him out of the play pen. Sometimes, I will carry him out onto the couch if I do not have too many other children here.
- During the day, if he is exceptionally crank due to tiredness, I will put him down for a nap (if we are home). On a trip to the park, I strap him into the stroller while the other kids play. He doesn't get upset, so he must really be too tired to play.

I feel like most of his day is spent in the play pen right now. It makes me feel like a horrible person....like a bad provider. When I really think about it though, I realize that he is very tired, and needs a lot of rest/sleep. If I do not put him in the play pen, he is miserable. I also cannot change his schedule, as it would disrupt the others' schedule here.

Hopefully, this passes. I can't wait for him to be down to 1 nap a day.

I think you are definitely doing the best that you can do here. Great job!
Truthfully, that is a LOT of sleep for an almost 2 year old. Unless he isn't sleeping at all at night (and I mean, AT ALL) that would be something of a concern for me. Is there anything else about this little guy that doesn't seem "right"? Physically or behaviourally? I could just be reading too much into a bad parenting scenario...

His parents told me that he has some trouble sleeping at night. He wakes up frequently and sometimes has trouble going back to sleep. He pees through his diapers a lot, and wakes up crying. They live in a 2 bedroom home. Their older son has his own room (12 year old) and the little guy sleeps in his parents' room.
His parents said that he goes to sleep at 9pm and wakes up at 6am on the FT daycare weeks. On the PT daycare weeks, he sleeps in until 8am. I think he naps at 1:30pm at home.
I have him PT this week, so I will see how that goes.
On Friday, he napped all morning. I put him down for a little nap around 8:30am because he was rubbing his eyes, yawning...etc... He didn't wake up until 11:30am. This was after several tries at getting him up. I even carried him out of the playpen, into the living room. I tried standing him up but he fell like jelly in my arms. At 10:30am, I gave up. I checked in on him because he was kicking his legs. I thought he was awake, but he wasn't. I changed his diaper in the playpen because I noticed it get full. (I take no chances. He peed through a diaper and soaked my playpen the week before). He still didn't wake up. At 11:30am, he woke up by himself. We had lunch, played for a while. I allowed him to stay awake until 1pm as I didn't want him to disrupt the others. He's not even 2, so he doesn't really understand that you have to be quiet during certain times. He knows to be quiet in the play pen only. He stayed quiet in there the whole time. He sang to himself in the begining, talked to himself. Never cried out to me to come get him. Around 2:30pm, he was quiet. I assumed he fell asleep. At 3pm, I had to get him up so that his mom could pick him up. When I went in, he was just laying there, about to fall asleep. I felt really bad getting him up. Once he was out, he wanted to play with my son. They played until his mom arrived.
Physically and behaviourly.... He seems to be going through Terrible 2s. Testing his limits. I don't see anything out of the ordinary, really. He throws his plate/bowl on the floor when he is done eating, but I don't think that is the worst thing he could be doing. lol. He has started to hit a little bit, but he is still a very compassionate little boy. If he hears another dck cry, he runs up to them and asks if they are ok and gives them a hug. He still has interest in activities (when he is not too tired).
Developmentally.... I'd say he's on target. He is starting to talk more. He is actually forming sentences. He's learned some french words (thanks to all the french speaking that happens here).

I think his sleep problems at night should be addressed. They should find another solution. Unfortunately, sleeping alone isn't an option for him, and I think that is what he needs. He always sleeps better here when he is alone. Unfortunately, that will not be possible here as more children arrive in my daycare.