I am not sure about FGM being ranked higher than Blue, who seemed to lead all the fairies. It is unclear I guess.
Blue is no doubt head honcho fairy, but I reckon once a fairy becomes a FGM, that means Blue can’t just automatically pull rank over her any more. They’re not quite true equals, but they’re as close as anyone gets to being Blue’s equal.
I know quite a few people are thinking that Blue might be the one who kicked Tink out of FTL, but I saw a tumblr post just before that suggested it was Rumple’s doing because Regina couldn’t become his monster if her FGM was still around. Makes sense IMO.