So to confirm (and this is a question!):
Piggyback licence, the only US ongoing requirement is the Flight Review (every 2 years) but otherwise nothing else American needs to be done (no medicals) as long as your 'main' licence is okay?
I have a friend (really, I have an FAA standalone licence!) who's flying his N reg using a piggyback but has not done an FAA flight review in years...
Thanks for feedback, Sam.