I have the same problem except 5 different age groups I yr old, 3 and 4 mth. old already combined, 2 mth. old and 1 week old. I am going to start combining the 2 mth with the 3 and 4 mth this weekend. Their pens are next to each other so they see each other all the time, a couple of the 3 and 4 mths. old got into the pen with the 2 mth. old and got along fine so I think it's time to try. The 1 week old are still in the basement in the brooder,but when it is time for them to go out I will put them in the pen next to the others and try in a couple of months to get those together with the rest.The 1 yr olds have a pen next to the others also and I throw BOSS out so they can eat next to each other and still be separated by a fence. Hoping my method of growing up separate but next to each other works out.
