Retired and caring for parent?

we're fortunate. we are caring for my mother-in-law who is not suffering from Alzheimer's but does have early stage dementia. she resides in an assisted living center where she has 24-hr care. the lucky part is that my bro-in-law flys in twice a year for 2-3 months at a time so we can travel. he lives in our home where he has a separate bedroom. he does this so mother is not alone in the sense that there is no nearby family (it's just us and my bro-in-law). I've heard of cases where care of an elderly parent falls to one of X number of siblings with zero support or assistance from the others. yes, we're very lucky.