How much room do you have, coop and run? What are the current ages of those chickens? Are you sure they are all female? How many chickens do you have?
Plenty of people have flocks that mix RIR, Buff Orps, Australorps, and many other breeds and have no real problems at all. In some the Buff Orps, BA’s, or even Silkies can be the problem, not the RIR’s. RIR’s have a reputation on this forum for being brutes, and some are. But some are no worse than any other breed. Assuming it’s just a breed and not some other factor causing the aggression, you may have just had some bad luck.
If you have sufficient room, once they mature if there is an age difference or you have a young flock maturing and establishing a pecking order, if you don’t have multiple roosters (and with enough space this may not be an issue), you may eventually have a very peaceful well-integrated flock. Right now I don’t know what is causing that aggression, so I have no idea what is going on now and I certainly can’t offer any suggestions. If you can tell us a bit about your circumstances we may be able to help with specific suggestions.