I got 20 week old laying hens from a farm near me to be with my lonely hen. I did the see not touch method. I have a run inside my big free range run with a small coop and I let them be in there for just a little while to get my hen used to them, I let them go and there was zero problems. I did the same with chicks (2 weeks old) and put them out there for about 2 weeks then I let them go, none of my hens have had any issue. Only time they get a bit annoyed is if one of the little ones try to steal their scraps. I believe the see but not touch method is one of the best ways to introduce chickens, but I don't just buy from anyone. I buy from a farm who regularly checks every chicken they sell for disease and treats them if needed. You cannot buy from them if they suspect disease until the situation has been full eradicated. I fully trust that every animal I buy from them is fully healthy. If you're just buying from anyone, I would quarantine so that your hen doesn't catch anything. I do like the chick idea that others have said where you put them in the coop where the hen can see them but not touch them.