I hear you. It's a whole thing... Not trying to complain or look for advice the situation is what it is my mother-in-law is a drama queen and it's easier to just accommodate them than stir up some bullshit.
The coddling never bothered me when my wife and I were dating but every year over and the older my sister-in-law gets I'm like "when is my MIL gonna make her stand on her own two feet?" like my MIL makes doctor and dentist appts and helps with the bills for her daughter even though she's out of the house. Vegan SIL is the youngest sibling and last to leave the household so it's a bit of empty nest syndrome coupled with an adult being comfortable with that level of prolonged mothering I suppose
It only really becomes apparent or "impacts" me around holidays so a few times a year. Suppose we're enabling the SIL too but my MIL will literally hold a grudge for the rest of her life so it's a bit of a stalemate. I defer to my wife and if she says make the pie I'm making the fucking pie lol
If you rise up to heaven I'll turn the sun to blind you
If you sleep deep in hell I have chains to bind you