There's only so much you can do, though, Lori. Yes, keep the humor flowing, but it really sounds like each of you need to find a way to get a break from caretaking at somepoint. Even if it's just for a few hours.
Perhaps your son could work independently at the library for a period of the day.
You are in such a difficult place right now. Caretaker to children and parents. It really is a heavy situation, I hope you know it's okay to say that!
Your son is so intelligent, but this situation is one more of life experience than intelligence, which he doesn't have a whole lot of yet.
Maybe the books will help, perhaps a grief counselor, I don't know the answer. But just take care of yourself and try to help your family do the same.

((hugs))

Neato