Where should I look for advice concerning caregiving involving 2nd marriages with adult children of both parents?

My father and step-mom are currently living independently far away from all of their children. My wonderful step mom is suffering from mid-stages of Alzheimer's. I can see that she needs assisted living now and will eventually
Require more skilled care. We're on good terms with her son and daughter and they're very involved,but I don't think they're as realistic as we are. I would like my father to stay where he is even if she has to move because I think it won't be long before she needs the skilled care. Is there any diplomatic way to approach this?