I don’t think that YTA at this time but I’d point out that you should be checking w them about prospective visit dates. You already visited and stayed in their home for NINE days when their baby was a newborn.

Having a guest (no matter how well meaning) stay with you for that long while trying to get into a rhythm with your first baby would be intrusive to me personally.

Maybe shoot for a weekend. Drive up on a Friday night, stay in a hotel. Visit Saturday. Visit Sunday. Drive home. Maybe you could try staying at a hotel so they have space.

There’s also a lot you’re not explaining here. Just because you didn’t spend time with your other grand babies as newborns doesn’t mean you can’t be close to them now.