I try to do everything and as much as I can to support my sister. There are 5 surviving sibling, 4 of whom are in agreement 100%. The 5th is only interested in what he can get from them. They supported him COMPLETELY financially for the last 4ish years. When they moved into the retirement center, they gave him Dad's truck, whereas, I bought their sedan. Point being, if they ever have to presence of mind to call him because they want to move home or get their car or another car, he will be an ally in any plan that gives him (more) money. He will lie to them about us & our motives. He's the sib that submarines anything good we are trying to do for and in behalf of them.
Work around him....make whatever plans you feel are in the best interests of your parents, and if all the rest of you agree..then you announce to him what’s been determined...not if he like is or not....”majority rules”.... If he balks...then he balks. ....He’s likely afraid the money issues will leave him high and dry.
Sometimes you simply don’t share information until you are ready, and ‘in place’ to...sounds like that may be how you will have to deal with him.
The "Serenity Prayer" was extremely helpful to me during Dad's passing.
So were the prayers of my church. Do your parents know the Lord? If so, prayers can always be so much more focused.
My prayers go with you and your family as mine were so graciously answered last year.