How to deal with difficult napper

Hello, I have had my littlest 13 month old for the last month and a half. She does everything not to nap! She will be falling asleep right before naop time but when she knows its lights out and playpen time she will find energy to scream. at first when she started I would lay down with her, rock her, everything. She is quite difficult to put down after sleep and half the time wakes up when put in playpen. last month has been hard as I have a couple older ones just over the summer who don't nap. I have been putting the little one down in the same room as my other 2 year old. He can sleep through anything so it isn't concerning to me that he will wake up. She will literally SCREAM for about 20 mins and then fall asleep on her own, but it sounds like I am ripping her toenails off with pliers slowly kind of scream. If she hears me make a sound in the house or seems me walking past the room she will scream even louder. I know she wants me to hold her all throughout nap time but that simply can't work long term for me.
How would you deal with this? I have another little one starting september who mom says needs to be rocked to sleep and quiet in the house to fall asleep. I was hoping to have this little one comfortable and falling asleep on her own before I get a new little one who will need sleep training but she doesn't seem to be getting any better.

Any advice, suggestions would be greatly appreciated!

Current child screaming house down for 20 minutes isn't actually that bad lol I feel your pain though honestly. I would under these circumstances to help this child to adjust asap is separate her. Put her in a totally different area of the house until she is less disruptive. Make sure you put her to nap awake every time, and do not sooth her. The fact that she only screams for 20 minutes proves that this is an attention thing and she can clearly get herself off to sleep after that. I know that you have the other child who can sleep through anything, but you have a new one coming in who by the sounds of it won't deal well with this child. If she screams, ignore her. If she is in pain, ill or unsafe, you will know the difference in her scream. Do not respond a single time otherwise you are reinforcing the behavior and she will continue. Once she has stopped with this nonsense, reintroduce her to napping with the other kids.

New child coming in I caution you now...It is interpretive that this parent changes how her child goes to sleep now prior to going to daycare. It is too much to expect for you to rock the child to sleep, its a disservice to the child and is just easier for the parent than crying it out. You will have to work harder to sleep train and potentially ten times longer if the parents continue to sooth them this way. In order to sleep train, child must be put down to sleep awake every time, it can not be a silent house, not a realistic environment, and you must let the child cry it out. This is at home and at daycare. Even if this parent doesn't get on board, you need to set the expectation from day one so this kid knows without question what the expectations are.

If my daycare kids happen to be woken up by a doorbell or phone ringing and they cry out, I do not respond. I give them plenty of time to try to self sooth and typically then they don't get upset in the future by the noise. Once someone goes in and lays down with them or rocks them, strokes them on the back or shushes them, they become reliant on this. It's not about being a hard ass or cruel, it is about allowing them to develop the independence skills that they all require. Having the ability to self sooth in one area, aids in their ability to do it elsewhere too.

Good Luck