That is a tough one! 2:10 is definitely not convenient. I would say lunch from 11:15 to 11:45, nap from 11:45-1:50 and then out the door by 2:10. If they want to catch a cat nap on the walk to school and home again then so be it (I am assuming you have a stroller for everyone - if not I would invest in one).

It is time to get everyone on the same schedule and fast. If a child is tired and cranky too bad, they stay awake until it is time for nap. They will soon learn that when you put them to bed it is time to sleep. Normally I have 2 nap rooms (daycare is currently under renovations). The ones that are difficult nappers go in a room together, those that nap good go in a room together. When nap time comes along, everyone gets their bum changed, put in their playpen, a happy goodnight and out I go. If someone doesn't want to nap and is bugging the rest I go in, lay the child back down and firmly tell the child it is time for bed, goodnight. If I need to go in again then I say nothing and lay them back down. If they are just laying in bed crying majority of the time I will just let them CIO. I invested in a video monitor and love it. Now I know exactly who is the one bothering the others. Now when they hear me coming down the hall they lay down before I even get to the room LOL!

As for asking the parents - NO. Tell them your new schedule (tell the one who naps 2x that it is no longer an option). If they want to follow it at home so be it, if not then so be it. I have my times in my contract so all parents know, if they use the same time I have no idea. I also almost always wake the kids up everyday. We have a set schedule and I don't go far off of it.