I wish I knew Darylh! If I had the answer to that one I would write a book which would make me rich and famous! It seems in every family there are some that do and some that sit on the side line. Yes, it would be easier if everybody would share the load equally but that is not what happens. One does the most, another helps a little, and several do nothing. Then you have the ones that do nothing and complain about what the others do.
As I have said many times before... the only person you control is yourself and how you deal with what you are given. Others make their choices and there is not much you can do about it. You can let it make you nuts or just go on without them doing what has to be done. If that means Dad ends up in a care facility so be it. Just know you can't make somebody do something they are not willing to do.
It might help to have a family meeting to discuss what needs to be done. Somebody can come up with a schedule of times or jobs that needs to be done. I have found it beneficial to use an online group for communication. That way everybody has access to all the information at any time... no excuses. If one of the family members doesn't pick up their share of the load there is not much you can do about it except pick up the slack.
Sometimes a big family doesn't mean lots of help with Dad