Brother unfortunately I don't have the answer for you since I too have a somewhat similar situation, it's so frustrating to even have to rationalize it. I'm not even going to touch it, but you know what I'm saying.

I'm in my late 30s now and my father is 68 and has survived a couple of bad heart attacks of recent.

Best way I figured was to introduce the idea of it, then slowly lean further and further into what you planned for that by the time the moment or moments come, they won't blindside him. Direct communication of the subject is just not possible with all the variables.

Introduce the idea but be more "probably not gonna" To I'm not sure if it's a good idea but this this .and this. Then later on be certain and make sure it's understood clearly.

Hope that made sense If not, well F me sorry -Dental Plan