I never knew other people besides me actually wanted feeder guppies as pets! lol! Are you still going to get RCS and scarlet badis? I have a regular badis badis in my tank and he gets along with endlers which are pretty much the same size as the feeders, and scarlets are smaller than badis badis, so you shouldn't have a problem.
P.S.: In the cup I see 5 feeder guppies? by 4 males do you mean the 4 + 1 female?