I go to some "lingerie modeling" studios where the "model" does this. Very early on she'll say "you can get comfortable if you want" which means it's OK to pull your dick out and stroke. Near the end of the session, if you tip them nice, they say "your hands and your cock can't touch me, but your cum can..." Then it's several squirts all of their belly n tits. The 2-girl session are SERIOUS nut busters.
I imagine her father loves to watch his daughter finger her pussy. He probably masturbates to her video periodically. If she was my daughter, I would do it.