This sale has left a bad taste and has done the forum no favours at all! The forum knowing the unrest regarding this should have become involved and obtained the answers from the organiser (Blaz) whose adsense will continue to fuel speculation!
It usualy only happens when yb's get out or get out and go into the wrong box. I like to put a batch of yb's down on the floor together at about 17 days, all the birds feed them and none of them get touched.
Unusual to be an old hen. Is she going into the wron box or are the yb's getting out onto the floor? If you know 100% its an old hen then you are better off without her, more trouble than she's worth.