At the risk of sounding like a lawyer at the bar (and we're talking scotch-and-soda bar), I believe the TAPPS rule (again, I haven't checked chapter and verse lately) is that the coach's kid(s), which would include situations of legal guardianship are eligible to play for the coach if the coach moves.
But everything else is speculation. And you guys KNOW I don't allow stuff like that on this board (by the way, I'm going to be gone next week and I TRUST you'll all behave ...)
Lemme tell you a story, really happened, and nearly tested the rule. Girls buckets coach leaves TAPPS member school A for TAPPS member school B. No problem, happens all the time. Except that coach's SISTER played for her at school A and transferred to school B; by the way, the kid was a real competitor on the court and for this level of play, was pretty darn good. My friend was leaving school B as AD at the time, and he advised school B's administration that she couldn't play for her sister, the new head coach, under this rule. But they hired her and took the sister as a transfer.
Fortunately for the girl and the school, TAPPS member school A closed during that summer and she was now eligible since the other exception is the closing of the original school.
Which reminds me, you could always tell how "important" the game against that Coach's team was by the height of the high heels the lady coach wore to the game. If she was wearing the stillettos coming into the gym, you knew you had a fight on your hands. If she wore flats, well, your team probably wasn't very good ...