I think it should be quite simple - if you're in the group YOU'RE IN THE GROUP which means you check in. Every day. Checking in is as simple as "Hi everyone, I didn't fall today." But don't limit yourself on what to post. You miss a day, then you better have a good excuse. Anyone who isn't checking in, is not really in the group. Maybe instead of having guard assigning groups we will do the following: We start with one group. At the end of the week, those who checkin every day, will become part of the group. A group that reaches ten will split into two of 5. Who goes where will be decided by the group - because at this point they are all active participants. From that point forward, anyone who wants to join a group will have to show their seriousness. They post in that group saying they are "applying for group joining." They will become active in the group, and participate over the next 3 - 7 days. If they "pass" by being dedicated to active participation, then they're in.
A better idea for checking in is to post on one's log, and then posting a link to your new log post in the group.
What do you guys think?