ulcer on chicken beak
I'd want it to dry out but I'd apply some Vetrycin on a QTip, not dripping, dab it on making very sure the chick doesn't breathe it in.
Attempting to introduce the chicks to your flock, it's safest with the recommended method of "see but no touch" .... Section off part of the coop for the chicks so they can be with the others but the others can't touch them for a few weeks. Or put the newbies in a wire cage with food/water, cage in the coop, again they're safe. Or make alot of hiding places that the newbies can be safe from the others. Make sure to add extra feeders/waterers and spread them out so there's no competition.