You need a bigger tank, or another tank, to do a Trimac with other fish. It'd work out great when the fish are 4 inches, 6 inches, maybe even 8 inches. But after a year or two, the fish become adult or late adolescent, they don't tolerate neighbors well anymore.
But, after a year, you've had the fish since they were tiny, they're starting to look really awesome, you won't want to get rid of them. You won't want to make "the decision" when it comes time to decide who has to go. You sure won't want to bring an adult specimen to some fish store where they'll give you "store credit" for it, and sell it to whoever asks for it first, no matter how small their tank or great their ignorance. You'll have to wait a while to re-home it here, may have to ship it, etc. So you probably won't
You'll either hope against hope that they'll get over it, stop fighting, stop chasing others constantly, whatever the issue--or you'll buy another tank and split 'em up. So just buy another tank now before you get the fish.
These fish are mean. And they get meaner--not nicer--as they mature.