Just in case I face Hooman’s nasty dilemma in the future, I posted the solution to The Sorrows of Young Hooman.
( Don’t Try This At Home, during our explanation to alert and educate children, teens and parents about the dangers of trained professionals. )
M1 uses both C1 and C2 on F1.
---------------- \---- ------------- C2 \- M1 C2' ) ) F1 ------------- C1' /- /---- ---------------- C1M1 uses only C2 on F2.
------------- C2 M1 C2' ) F2 -------------M2 uses only C1 on F1.
------------- C1 M2 C1' ) F1 -------------M2 uses both C2 and C1 on F2.
---------------- \---- ------------- C1 \- M2 C1' ) ) F2 ------------- C2' /- /---- ---------------- C2