Please isolate the hens you are getting! The biggest problem getting anything other then chicks for your flock is that you don't know if they have any problems and if they do they can spread it. Rule of thumb is to isolate for one month, for some this is just not possible. While isolated check them over for a few things. Does their poop look normal? (not green, yellow, or frothy) Are their legs red? Do they have bite marks or q-tip look to the base of their feathers near their vent? Are their combs bright or pale? Do you see bugs either on them or in their poop? Do they look drunk? Are there black spots on their comb? Ask the person you are buying them from if they have a worming schedule and if so what they use and how often. Let us know if you have the setup to keep them separate for a month and if not we will do the best checking with you to give the best integration possible with limited time. Also, answer these questions for us as you can so if there is a problem we can walk you threw it to get it taken care of before it infects your entire flock. If there is a problem knowing if you would prefer natural or chemical treatments would help us in giving you advise.