Sounds like you have perhaps figured it out, Eb. From what you have posted, it sounds like the most sensible solution is for your sister to move to a one floor apartment and moved closer to one of the grandchildren so they could more easily offer what assistance she would still need.

If you completely uproot yourself so that your sister does not have to make any changes at all, chances are good you are going to end up regretting it. In addition, I'm guessing your sister is old enough that you do not know how long she is going to be able to function with the minimal assistance you indicate she now needs. You could very soon find yourself unable to provide the level of care she ends up needing.

Another alternative you did not mention is for her to move to Juneau, and the two of you find a one floor apartment or house there.