the way i see it anyone who was "presumed dead" could easily be a FM in disguise
any person who made a long journey that wasn't detailed could easily be a FM
but the bigger question is do Varys and LF know of the FM because i doubt they would be so confident knowing assassins out here switching faces
Littlefinger i doubt, but Varys knows all type of shyt, he's from the free cities so knows how they get down. But the FM is like the illuminati, if you aint in it, you cant do nothing about it.