Feed them IN their normal enclosure*...at night (or evening)...wait until they're peeking out of their hide (BPs are ambush-predators!) rather than when they're
exploring cage...DO NOT handle* your BP prior to offering food (disrupts feeding instincts for many, stresses snake). And don't feed snakes that are blue (in
shed cycle) nor any that have not completed the shedding process. Put their thawed & warmed prey on a "plate" (of some kind, cardboard ok, to avoid sub-
strate sticking to it) ONLY IF they don't grab it from tongs with a slight wiggle to appear life-like. And yes, if the old shedding skin is coming off EASILY, it's
fine to help out gently...I probably would too.
*Biggest (but not the only) issue that worked against you was putting your snakes in another container. You got lucky the first time, that's all.