I study ants. If you find a species, that doesn't sting, that is very un-aggressive, specific ant species may be perfect as feeders...
HOWEVER, and this is a major however, many people, use poisons to get rid of ants, you need to make sure none of your neighbors do or that could kill your frogs. Furthermore, many species of ants are highly agressive and could potentially hurt a dart frog, so if you can't be sure the ant doesn't sting, spray lots of Formic Acid or have a bad bite you shouldn't use it.
As for a few surviving and setting up shop. Not going to happen. Ant workers cannot set up a new colony without a queen, they are usually infertile, or if fertile, only lay male eggs which they cannot breed with (there are always a few exceptions, but the vast majority of ant species follow these rules). I have fed ants to darts before (long time ago and not to my current frogs), and it is amazing the different reaction you get when compared to them hunting fruit-flies.
Saying all that, I wouldn't feed them ants unless you are completely aware of what you are doing and only a few at a time.