Decision to be made about culling babies

My neighbor bought 36 chickens ranging from 3 days to 4-5 months about 3 weeks ago at an auction. They brought them home and put the 8 -3 day old chicks in their garage and the older chickens they placed directly in with their flock. Mistake, I know. Within days their prior 30+ pullets and 2 roos were lethargic and the layers completely quit laying and several of the older birds died. To date they are up moving around and acting normal yet are not laying.

This week the owner had a family death and left on Fri. and won't be back until next week. She called me on Wed. to see if I would take the 8 babies. I said yes without thinking....just trying to help. The 8 babies are currently quarantined away from my laying flock.

The advice they've been given is to cull the entire flock. Another board I read on said to cull the older chickens and keep the new ones that they are carriers but do not have whatever disease it is.

What do I do with these babies? Return them...cull them???

Because of their age I wouldn't put them with the others for at least 7-8 weeks. They act normal, look normal but I don't know if they were sick any during those 3 weeks prior to my getting them.

Don't know what to do??? HELP!!!

 

Sorry...must not have explained myself well enough...they're MY chicks...she gave them to me.

 

The main symptom now with her older flock is that they are not laying.