I have two siblings, both sisters and both younger than I. One sister has three kids and the other two. With my four (I have both the oldest and youngest) that makes nine grandchildren for my parents. We are all busy and all live in NW towns with a few hour drive separating us. It is very difficult for my parents to make it to each child's home or party on their actual birthday. A few years ago my mom came up with the idea to have one big group "birthday" party for the kids. It has been a big hit. We have done lots of fun things. Last year we rented a house at the coast for a couple of nights. This year, we kept things a little more simple and went for a hike and then played minigolf.
Our "birthday" or rather, un-birthday party was this past weekend. I forgot my camera so these were taken on my phone.