The living doll thing would bother me, especially if my kid was not into dressing up.
It suggests the grandparent just wants to display the kid as an object.
If my kid was into digging in the dirt all day, and the request was dress up clothes....
But if you are leaving your kid with them presumably you feel comfortable with the care they provide.

"Thanks Margie. I already have a packing list I use for Emma but will try to remember to throw in an extra dress or two for you. Have fun with her!"

In about 2-3 years, it's likely that the living doll is going to refuse to wear dresses at all, if she is like our daughters. So let grandma enjoy it while she can

OP, listen to yourself. My MIL would rather do a crossword than see her grandchildren - who live 5 minutes away. And no, I've never done anything to her, or anything like that. She does what she wants when she wants, to an extreme, and wants the world to know. She could be compensating for what she perceives is a lousy life (though better than being left on the farm, literally) - or it could be that MIL was nasty all along.

Point being, she is never interested in anyone but herself. If someone told me MIL - no anyone loving, would watch our child while we went to a wedding (!!!) I would say where do I sing up.

You don't have to be at her beck and call, or answer every text. If you have problems with boundaries, so will she.

Good God woman, your MIL is kind and loving enough to watch your child so you can socialize (!!!) Grow up and be grateful. And send her over here. We will gladly adopt her as our kind, selfless grandmother.