I hope the grandparents who are local were totally oblivious. I don't want to think it was on purpose.
I would say the non-local grandparents need to open up a conversation. First with their own child, and then maybe the spouse. Discuss what the relationship should ideally look like. Get them to buy in. Then, ( not knowing the dynamics at work here) perhaps a small meeting with the other grands. At this early stage of grandparenting, everyone is finding their roles. It's definitely not too late to ensure all have an engaged roll with these precious young humans.
Nuts and bolts of making it happen? FaceTime and Skype. Voice recorder text messages and emails - yes, I know at this age of requires parental involvement to share with them. Send them a self addressed package of themed pictures to color in and return to you. This can be built on as they get older - color me a card for Christmas, write me a short story, etc . Once they're older, you can Send a journal type notebook back and forth, or even do it online. Each person writes a paragraph of part of a story until it's filled up. Send them a book, and you have one too - then read to them through video. So many ways to connect!
Additionally, I'd ask to have alone time with the kiddos. Since they're not in school, can they go home with Grandma and Grandpa for a weekend, then a week at a time for visits? I take mine on vacation every year for a week in the summer (it's Nanny and me time) and alternate holiday weeks as well with my hubby.
It's very possible to make it work, but it requires WORK on the part of all parties.