google some info on Dutchmaster Reverse. I have heard mixed reviews, but at least a few almost identical to your situation in which pollenation of younger plants was prevented...
Technically, though, from what I have read it really needs to be applied at the outset of 12/12, and then again ten days later - (it is really more of a 'preventative' for hermies; supposed to steralize male organs)
But those who used it on the younger plants were past this point, and saved their crop.
PS. even if you DO save those teens, you need to remove them and wipe down THE GROW AREA with a light bleach solution - not the plant, the GROW AREA - lights, walls, mylar, everything - and then you can bring them back in and hope for the best. They might have pollen on their leaves tho, which is bad and in that case cleaning the grow area probably will not help. I wonder also if a spray down with light rubbing alocohol solution, like when dealing with pests, might work. Be sure if you do try this to heavily spray down your girls afterwards with plain water or the alcohol will burn your girls.
PSS. my first post! lol.