Michael Lodge, NCPM, CRTP
There is an excellent group out there called "Grand Kids Matter". https://grandkidsmatter.org/ If your a grandparent, sign up for their newsletter. It is a great site to help you become a better grandparent, even being a grandparent takes work on developing solid relationship.
One of the issues is the custodial grandparent. I have a couple come into mediation relating to their custodial grandparent role of the two grandchildren. However, both grandparents were divorced and did not like each other, but they were the custodial grandparents and needed to work out issues between the two of them to raise their grandchildren. Here is a good link for you who are custodial grandparents: https://grandkidsmatter.org/category/hot-topics/custodial-grandparents/