Get an attorney. Negotiate the percentage and hope it doesn’t happen before the holidays :(
They will prompt you to get mom to write a will which, if you don’t have, you will have buzzards from all over the country trying to file claims against her and your dad’s estate.
Oh, there are wills and trusts and whatnot. It’s the secret visits to attorneys and signed documents that happened relatively recently that have me questioning what is going on.
My mom is too affected to be legally anything right now.