try here...
https://www.backyardchickens.com/a/adding-to-your-flock
i would start by letting them see each other threw a screen or some thing like that ..if you have room in the brooder [depending on how big the orps are ] and split the brooder so they can see each other but not be able to get at each other ..the more they get used to each other the better it will be when they first meet ..i split my run and my older birds were a yr old when i introduced the new girls that were about 18 weeks old ..i had them on grower finisher feed and my older girls were on layer feed ..so once my new birds could eat layer feed i started the introduction..at that age it was pretty tough ...but with your birds all on the same feed .i would slowly start getting them used to see each other threw the screen or fence ..you dont want the screen big enough for them to stick their heads threw it or they may get bit by the bigger birds..
hope this helps ..good luck ..
https://www.backyardchickens.com/a/adding-to-your-flock
i would start by letting them see each other threw a screen or some thing like that ..if you have room in the brooder [depending on how big the orps are ] and split the brooder so they can see each other but not be able to get at each other ..the more they get used to each other the better it will be when they first meet ..i split my run and my older birds were a yr old when i introduced the new girls that were about 18 weeks old ..i had them on grower finisher feed and my older girls were on layer feed ..so once my new birds could eat layer feed i started the introduction..at that age it was pretty tough ...but with your birds all on the same feed .i would slowly start getting them used to see each other threw the screen or fence ..you dont want the screen big enough for them to stick their heads threw it or they may get bit by the bigger birds..
hope this helps ..good luck ..