I have two daughters and the older has a son about to be 14. She and the father have not been a couple since he was two. His father is very involved and they agreed to share parenting. As mum's parents, granddad and I did a lot of childcare after nursery/school etc, but the other grandparents are very much a part of grandson's life too. We get on well with them and have seen them at events over the years. Grandson goes with his dad to visit them quite often and both parents have spent several Christmases with his family, and been on holiday in Italy to their family and to a wedding there. Grandson also stays with them sometimes and he and his younger sister love being with the cousins.
Not just that, but daughter then got married and had a daughter who is just 5 now. Grandson's dad's family have always treated her like another grandchild. Other gran knits wonderful things like doll's clothes for granddaughter. granddaughter went on holiday abroad and also to a wedding with the family in Italy with her mum and brother and goes to visit the family.
Grandson's dad is the favoured baby sitter. Daughter divorced her husband, granddaughter's dad, three years ago. That was a little less amicable but he is involved with his daughter too. His parents are dead so no role for them, except his other daughter, living abroad, is a big sister to granddaughter when they can meet.
I think if everyone loves the grandchildren and tries their best it can work well. For the five year old's birthday 3 weeks ago we had a zoom party and grandson's father's family were there in strength. I think seven windows were theirs and two young cousins even brought two hens in for me to admire. I occasionally exchange emails with other gran too. I like her very much and we congratulate each other on how well grandson is doing and hear news about the family.