I'm confused... You said your other rooster always tries to mate with "her", but you can't have roosters in the city limits, so you'd have to rehome "her" if she's a "he"? What will you do with your other rooster? Did I misunderstand, or did you have another rooster too?
I'm curious because we have a silkie, "Floof", that looks just like yours, except with more red, and I am thinking it is a Roo too. As far as I can find, the "calicos" that are colored like this appear to always be boys, with the females having the red more on their chests? (I have no idea, it's just what I've seen in trying to figure out what we have here!) My poof ball is getting what look to be streamers, and is also getting pretty confrontational and feisty with one of the pullets (which appears to be a hen, but I wonder... she is pretty crazy and obnoxious) who picks on him all the time, so I'm pretty sure he's a he. Anyway, my other Roo, a bantie Ameraucana cross, who is about the same age as Floof (4 months or so), is the sweetest thing, and the two boys never fight. They each have their own little group of hens, and seem to be just fine (Crazy hen is off on her own, doesn't like either "family"). We plan to keep them together so long as nobody fights, and it seems so far that they are living in peace. I think it helps that Floof and the other 2 silkies stick together, and the bantie has reign over the 3 big brahma hens. We shall see... Anyway, I was just curious because I'm hoping we have a good group that will coexist peacefully (minus the Crazy one if need be), and wonder if you couldn't do the same, since you say she/he's your favorite?!