My sister has down syndrome, short term memory, sundowners and start of dementia. I have siblings retired and never call or help. She started going down hill in 2016; in hospital (3) times, teeth issues (outpatient, pulled 8 bottom ones and new dentures a couple months ago).
I grew up with a family that kept their DS daughter home as long as they could. The mother went into an AL and was able to bring the girl with her. (Actually, she was in her 60s). The girl had gotten violent as her Dementia progressed. I am sure if she hadn't passed before the mother her siblings would have placed her in LTC.
Here’s what I suggest and you can do this or not, as you see fit: Draft a letter to your siblings. You could even ask an attorney to help. Letters from attorneys always seem to get immediate attention. Send it signature required to make sure they got it. Write that you are notifying them you are “going on a break” from caring for your sister. You can do this a few ways. You can inform your siblings that their sister will be coming to their homes for —-weeks or months a year. Or, if your sister doesn’t like change, tell them you have made reservations for a vacation and they must decide who will come to your home to care for Sis. Also, if you have been paying for your sister’s care, stop. File for Medicaid. Your siblings will not kick in at this point.
You must follow through on this if you expect any break. If you don’t, nothing will change.