If anybody's feeling guilty NS, that's on them, not you. Hell, we all go through life doing the best we can as individuals. My Mom who some know just passed over, was in an assisted living facility mostly for her own well being. She was surrounded by family when she passed. I could not be there but will get down to Pa. in the spring. It's not like I don't know where she is.
I think the greiving/ caring process that the Dr Phil's of the world come up with are way over-rated. Yesterday was a down day here on the farm & I was looking at some real old family pix when I found myself with a tear or two. In some circles I'm sure the tears were not up to expectation, but, they were mine & for real. Again, we do the best we can in any given situation. NS, enjoy those lil girls while you can--they grow up & get off on their own as you stated. BUT, it sure is nice while it lasts.
PS--don't even get me started on how to raise kids by Dr Spock