I don't know the exact situation you're looking at, but I have been involved with situations that may look sketchy from the outside, but are perfectly legit.
For instance, I know a home schooled athlete that competed for the team at the school that was closest to her house, but in the middle of the season it was noticed by some school officials that she actually lived across a school district borderline for another school farther away. I don't know all of the details, but the WIAA told her to move to the appropriate district, but that since it wasn't an intentional thing she could finish out the season competing for the new team (just for last three meets of the season).
Also, the school next to ours does not have an XC team. During the regular season the athletes from that school who want to participate in XC come train and compete as members of our team, but when the championship season rolls around they need to borrow track jerseys from their school and compete under that banner (still train with us and we still transport them). On paper though, it looks like they ran all season for one school, and then a different one for the district and state meets.