Dad is letting them come, so he won't change his mind. Over the years, Mom and Dad's families came frequently to visit. It never changed our lives though. (Well, it did, since I was the only girl and had a full sized bed, so it became our bed. Still, not a problem, other than my room had to be picked up the entire time they visited. Apparently, adults don't like stepping on Barbie shoes when going to the bathroom in the middle of the night. Who knew? lol)
We'd visit with them when they came. Ate dinner with them, but because we all ate dinner together anyway. I have no idea what my parents did with them during the day. We'd all do what we usually did, so I wasn't home or I was in my bedroom then.
Never heard of anyone who thinks it's up to the kids to entertain the extended family. I think my parents might have been appalled with us entertaining them. All I can imagine is taking my aunt or grandmother with us when we went hunting for more reptiles or more food for the reptiles. (Reptile food -- minnows and bugs. Lots and lots of bugs. lol) Or, imagine taking them to our secret fort. Would they gather supplies with us? How are they at bundling hay for the thatch roof?
Even as an older kid -- teen or early 20s -- would they really want to go to the library with me? To enjoy some very-loud Led Zepplin or CCR? To go to the mall and check out the craft stores and record shops? (Come to think of it, my grandmother would have loved the craft shop. lol)
It just wasn't ever our responsibility to take care of guest staying at their home. Their guests. We entertained our own guests.
I was fortunate. My parents were getting a divorce before Mom died. Even then, they didn't let us get involved in their drama. I didn't even know Mom hated Dad's Mom. I didn't know Mom's Mom hated Dad. None of that came out until Mom died, and her family felt free to tell what they really thought through the years. And even then, it was with the greatest respect to the knowledge that we do love Dad. (And, at least some of us loved his Mom.)
Seriously, South. DUCK! Do what you have to do to avoid the drama. Two people in your house isn't that big a deal, as long as you don't feel responsible for their care. I do have aunts and uncles I never got to know that well. They even stayed at my and my parent's house and I stayed at theirs. Ultimately, enough going on that it doesn't matter. Kind of like walking by a chair each day. It's there all the time, but unless you need a chair right then, it doesn't affect your life.