Just a few more thoughts to toss in...
I often hear the argument from homeschool parents that children don't need same age friends - that they enjoy being with all ages. There's some truth in that, BUT...
It's been my own observation that while it's absolutely delightful and heart warming to see a group of homeschoolers happily playing and including all ages, that doesn't mean they don't also want same age friends - especially, but not only, as they're coming into ages 10 and up. And there comes a time when that can drive them to want to go to school, or demand to go to school, if they're not given good opportunities to have same age friends. I think that's just a natural human tendency. Parents can't just be complacent and tuck into their individual nests, thinking everybody's going to be as satisfied with the arrangement as they are. I've seen that backfire big time, causing families to have to give up homeschooling.
I've also seen budding teens, as young as 10 or 11, get really fed up with having to always be part of groups where the needs of all the younger children have to be met - it can be pretty limiting, and the needs of the older ones can get pretty marginalized. Not only that, but it's not that uncommon for parents to start looking at them as built-in help in looking to the needs of the younger ones. The parents often think of that as helping the older ones learn to enjoy responsibility, and being a great thing for all concerned - but it can get old.
And another issue - but an important one - I've known them to express the passionate need to have some separation from their younger siblings, even though they might otherwise like them and get along with them just fine. Maybe that's just a natural part of individuation.
We had one activity group in which there was some real animosity between parents, because those who didn't have older children didn't understand why there should be a separation of activities. They had their minds made up that their children would do just fine in the older children's workshops - and it was really maddening to try to make them understand that those older children really, really wanted/needed some personal space for a change, with just their own ages, without their younger siblings there. And that was pretty awkward - because obviously no one wanted to have to tell everyone, "Look, Joey is angry about having to have Billy around all the time! He really wants to have some space to himself once in awhile." The ones who didn't have younger siblings weren't as passionate about needing the separation, but they still relished the idea of having that kind of separation for some group activities.
These were all really nice kids - they just wanted their own space for some activities. They wanted it so much that they even developed their own separate teen group that met away from the normal park day with just one parent facilitator. I think that was unfortunate, because it mean that their parents were no longer connected through a park day, and so weren't in close communication about a lot of important issues - it would have been nice for everyone if they had felt supported enough to keep coming to the main park day and having their own space there.
Just some thoughts to mull over as you go...
Lillian