See here Dana,
Minifob thread 
Fobble - Im hearing ya. I too think its great that the MIL wants to have Minifob for a week, but I think a week is a looooong time, plus if I read it correctly, she will have the other kids as well? The overnight idea seems like a good start at least, then MIL will feel like she is getting a *chance* and you guys get a nite out.
My Mum is well and truely frazzled having the boys for a day and just over night, yes they are a handful, but they are just typical boys.