This is very touching. We've just become grandparents for the first time - we live in Cardiff, they live in London, so not nearly so far as the USA. But the problem is similar - how to have routine contact, how to help, babysit, do practical things; how to make sure our lovely little granddaughter, Laura, knows who we are and becomes attached to us.
On the plus side, when we see them, they come to stay, or we stay with them, it's not just brief drop in visits, it's round-the-clock.
But one day, maybe, especially if more grandchildren come along, we may have to decide to move back to London - hmm. Not a hugely attractive prospect, and very expensive.
What to do ....