Nap time placement

[Polkaroo]

I would try to put #4 who sleeps for an hour into your son's room. Maybe she wakes up because of her brother and would sleep longer with another good sleeper. Put #3 in his own room with a noise maker (waves, heartbeat, rain) to help him relax, put #2 and #5 together in the sleep room. They might be able to get into the same sleep pattern and comfort each other and maybe would stop waking up all together.

I know your son is nice by himself but maybe if you put the other best sleeper out of all of them with him with no one waking her up she might sleep even better. I would try like 5LM for a week or two to see if you see any improvements. If not you can then remove the second child from your son's room and try something else. Not sure if this makes sense. Good luck and keep us posted.