OH! I did not know your nephew lived with you?! That explains the rest of the post that I wasn't sure about.

Sounds like you've just got yourself a more extreme version of unwanted-houseguest than I have had!

What's the set up of your house like? Can there be a play room set up for the child so that he's primarily located in the bedroom or his playroom? Can you guys set up like... a schedule for various chores while she's there? (I don't know if you would possibly find it aggravating if your guest did none of the chores.... who knows).

Can you plan to go take a walk every day to give you time away from everyone? Walks are usually pretty relaxing too.