@chickens really is correct. You are taking a risk in mixing chicks from a breeder with hatchery chicks. As long as you are aware of the risks then that is up to you, but be aware that even if the local breeder is NPIP certified, the chicks could carry Marek's disease which is a devastating virus. The breeders chicks may even have some resistance to it, but the hatchery chicks will not. I'm not a fan of the vaccine for Marek's but it might be worth paying the optional extra to have the hatchery chicks vaccinated in this case.
If you intend to keep them all in the same brooder then I would agree with @oldhenlikesdogs and give the potentially weaker chicks that have come via the postal system a few days to recover and acclimatise to their new home before adding the local ones which should be stronger.
If you intend to keep them all in the same brooder then I would agree with @oldhenlikesdogs and give the potentially weaker chicks that have come via the postal system a few days to recover and acclimatise to their new home before adding the local ones which should be stronger.
