Maybe give her a bath to wash dirt and dust off her, dry fluff and put her in a clean brooder crate in an area away from the others, wait for a few days to acclimate, then introduce some 6 day old chickies.Interesting idea. Sort of taking a bet that Tassels is less contaminated than everyone else.
Hmmm.
I put 4 day old chicks under unproven Sophia and she did great.