Well, my situation is a little different, as MIL lives with us part time. Mother living with adult daughter is common in DH's culture. It is not so common to live with an adult son, and it entirely depends on DIL - me! DH wanted to give his sister a break, as MIL has been living with her for over 20 years. She is now blind from glaucoma, although otherwise in good health. She was with us for 3 months last winter, and we will have her come this winter. The house we are building has a room for her, and we look forward to her coming.
I tell you, I earned a LOT of points by having her stay with us last winter. SIL finally likes me, I think. MIL told everyone that I treated her like my own mother, which was a HUGE compliment. It wasn't that hard, as I genuinely like her. And, DH had time off due to parental leave, and he took over much of the cooking while she was here. And that sometimes required 2 dinners, as she is a strict observer of lent and did not eat any meat during that time. (DH is a big carnivore. I would have been fine with fish or vegetarian during that time, but DH made a fish dinner every night, and usually a meat meal, too). That made things even better! It may change this winter, as he and I will both be working full-time, and DS will be in daycare. But, with the new house, more space, I think we can manage.
Our house is also open to my extended family, should any of them need or want to live with us. Not likely to happen for quite a while, though.
SO, the conditions are quite a bit different in our family compared with yours, but I wanted to throw it in the mix!