I got my first 2 chickens(Red sex links) 2 1/2 months ago, and they started laying almost 8 weeks ago. Now I just picked up 2 young Ameraucana pullets, I am guessing around 10 weeks, I was only told they were 2 to 3 months old. They are about a third the size of the red heads it seems. I have them in a seperate coop for the quarantine period, but have attempt to let them run loose in the backyard for around 10-15 mins while the red heads run around to start getting them acquainted. Is this a good idea for getting them used to each other? Once they get a little bigger and the 30 days is up, I want to have my coop designed a little bigger and have all 4 together as a flock.
Odd thing about the 2 new "girls" is that one stands more upright than the other and tail stands a little more upright, and has a little bit of comb on top, while the other stands more down, tail down, and has no comb at all. I got the one I am thinking is actually a girl last wednesday, and after a few days decided I didnt want her lonely in the coop alone, so I picked up another from same chicken breeder this monday. The one I just got is the one I am not sure if it is actually a girl. Breeder says she thinks its a girl. Any way I could tell or do I just wait and see lol?
The one on the right is the one in questioning
Odd thing about the 2 new "girls" is that one stands more upright than the other and tail stands a little more upright, and has a little bit of comb on top, while the other stands more down, tail down, and has no comb at all. I got the one I am thinking is actually a girl last wednesday, and after a few days decided I didnt want her lonely in the coop alone, so I picked up another from same chicken breeder this monday. The one I just got is the one I am not sure if it is actually a girl. Breeder says she thinks its a girl. Any way I could tell or do I just wait and see lol?

The one on the right is the one in questioning