there is another thread I recall where someone did add pumpkinseed/BG to their tank & it eventually released white worms. they treated with parasite clear & no luck, so they want to dump it back. + now their own fish have to be infected.
so one risks introducing foreigners to your tank. even after QT for weeeks may not rid them unless u treat with some strong meds, b ut then again the new fish may not seem sick & are use to b eing carriers, until they get in to your tank.
hope u get my drift learn from others' mistakes. keep em separate.