I for one appreciate all the discussion around this topic.  I pray for the OP, as I feel he knows the answer to his own question.  I will offer that the other siblings will be at the table to settle the estate.  No value will be offered to good will to parents over the years. If a father passes away first, mom will correct the equation and split the remainder up equally.  All that being said, if one or both of the parents get an extended nursing home stay it is a mute conversation.  Secession planning while very easy from the outside is difficult to achieve and takes tremendous effort on all parties to make it work.  This family situation has serious issues and does not appear to have a good ending.  Very difficult situation.  Best of Luck.