It may be better to dose them individually. Personally, I'm not a fan of mixing with feed since it's dependent on the bird to eat enough for the medication to be effective.
I agree with @EggSighted4Life Safeguard is not what I would use for birds that are molting since it is known that affect...
@dawg53 and @coach723 may be able to give you some tips about worm management.
I have birds running loose too and it's just been a wet year all around, swampy and nasty.
I have not seen worms in any of my bird's poop. I'm sure they are eating all sorts of things from the amount of digging...