If it were one of my silkies I would say shove the whole bunch of them under her, or even Dorothy who really had the bad broodies.Don't forget my Marek's issue. I think day-olds and hatching eggs are a no-go for me unless I was to go the long and heartbreaking route of trying to breed a flock that was resistant to whatever strain I have in my environment.
By the way, with the exception of Piglet I don't think they are imprinted on me. They clearly view me as the agent of imminent murder and will do anything to avoid me. Piglet is an optimist and believes anything new in her surroundings will result in food so she is more friendly.
I could certainly try and put one under her at night - I would love to hear from anyone who has experience of having a broody adopt an older chick. She is also less than a week into being broody so wouldn't she be puzzled by the appearance of a chick?
I would be interested also to hear of anyone has tried this?