Quoting kate & tilly:" I'd just do the one party. Everyone else is acting like they're the ones who are three."
Quoting clay matthews:" I'd just do one party. The grandparents need to stop being petty and put on their big girl panties long enough to attend your DD's party. It's only a few hours out if their day"
Quoting MommaSav2:" I would hold one party and tell them that they are all invited should they choose to attend. I would ... [snip!] ... my child to have all the people who love him/her around them at once and have a great day. It's not about the grandparents."
Quoting 3 little monkeys ♥:" My daughter is turning 3 on Saturday. My parents are divorced and sometimes they get along, sometimes ... [snip!] ... do then you're welcome to come tell her happy birthday another time and bring her present over if that's what you wish to do. "