I just received chickens somebody did not want anymore. I received another one later from another person. How do I get the first batch to accept the single pullet?
First, there should be a quarantine time of around a month, but most of us do a couple of weeks at least, unless you know the people from whom you got it haven't been dealing with anything. You don't want to bring her in to get the rest sick in case she has anything.
After that, the "see but no touch" method works best. That's putting your pullet in a cage or pen where they can all see each other. After about a week, try putting her with them, but monitor this in case it doesn't work. There will be some adjustment time for the rest of your chickens to make sure she knows her place in the pecking order.
Integrating a single bird into an existing flock is always the most difficult integration unless that single bird happens to be a rooster. You'll want to create an area within the run for the new bird where she has everything she needs. She needs to be within sight and sound of the rest of the flock but set up in such a way that they cannot touch her. Leave her like this for at least one week.
If any of your flock members seem to be interested in her in a good way you can try to put that bird in with her after one week and see how she does. If they get along leave the pair of them in there for another week. At that point you can release them to mingle with the rest of the flock. Before doing so make sure you have feed stations set up everywhere! I use flat stones and stumps as feed stations in addition to my feed troughs and feed bowl. The flock should have a lot of enrichment in the run like having lots of organic litter to scratch around in and branches or other objects to fly up and perch on.