Did something similar. Had joint accounts, parent sand child. When the person was sick the siblings set up a joint account for themselves for all bills relating to the parents care and the the estate. Which is useful as the bank will lock the joint account if one of the account holder passes. Credit unions don't do this. It passes directly to the other account holder. TBH I found the banks, not that helpful. Only for we had taken control of some of the funds, and could print off all transactions, or copy them to excel. Going thought the bank during probate would have taken ages and greatly delayed everything. At least with money set aside, you can cover all the essential bills in a timely manor.
But it obviously requires full confidence in family members. There are many disputes about money.
I would also say get all the paperwork squared away. You might think your parents are on top of the paperwork but they often aren't.