I'd say to let them be together
When I first got my mare last year the guy I bought her from showed up with her and just opened the gate and led her in. There was squealing and my gelding ran around buck kicking and making noises. By the end of the day they were friends. By the end of the week they were in love and married =).
They lived together for the last year and she was definitely on top, but she was always moving him around and trying to keep him away from the hay, because she is much larger than him, but I recently leased my gelding out and put my mare in with my mini mares because she was lonely. She really seems to have a different relationship with the mares. She touches faces with them and eats very close to them and doesn't chase them off. There is more squealing going on, with 3 mares together, Squeal stomp, squeal stomp.
and I think that my mares seeing each other for 6 months over a fence did make the first real meeting pretty easy going because they did get to know each other over the fence.