Wet chicks chill, I don't think you have much to worry about since they were just with their siblings from the same place. They are chicks so they will be quarantined from and other chickens since you don't have any. If they have something, bathing them isn't going to change any internal issues and if they have mites, I'd just give them diatomaceous earth. I use pine shavings and have never had a problem. Some people swear that they can get various things from them but I've never had so much as a mite on my chicks so I don't think there is a problem with pine. I don't use cedar so I can't comment on that, it does splinter on the soft pads of guinea pigs so it could do something to chicks feet, I don't know for sure though.