I have two brothers (there was a third) that all hatched together and live fine in a pen with the ladies. There's also a tiny (12 oz) geriatric serama roo that lives with them and they've never bothered him in the least. I also have a bachelor pen with 5 Icelandic cockerels, a CCL roo and an OE cockerel, everyone gets along fine. My experience has been my Icelandics aren't terribly aggressive with each other.
Good luck, have fun with your new birds.