Your children are keeping me up at night

I couldn't sleep last night. I kept thinking about the neighbor kids. Ya, not my own, who were sleeping peacefully. These kids are new to the neighborhood, and nice kids. The oldest is 7, a girl and a new friend to kid#1, the other is 5 and a boy. It turns out they have a rule, where the oldest can only go play with her friends if the young one can tag along. I don't have any 5 year old boys to entertain him, so it seems like an unfair rule to everyone. The older kid, my kids, me, and the 5 yr old boy. I don't understand why they don't get to have their own friends. They are a military family, so I'm certain that it comes from moving every few years and having to rebuild friendships over and over. My dilemma is trying to figure out how to allow the older kid to play with mine, while sending the little one back home to make his own friends with kids his own age. I think the result is going to be that neither of them are going to be able to play with the local kids. Allowing the one to play means essentially committing to babysitting the other. I feel bad for the kids and a little bit angry with the parents.