I'll be interested to hear how this mystery turns out. I went back and looked at the Australorp and while the hackle feathers look suspiciously pointy IMO, the saddle feathers and tail look hennish and the comb is certainly not overly developed so....since the middle one in your pic is a BSL and there should have been no doubt of its gender at hatch, perhaps you really do just have a crowing hen. I understand about being a good neighbor and all but if the crowing is only first thing in the morning and only before they are let out of the coop, I'd be inclined to hold onto all of them until you know for certain one is a boy AND he is crowing all day long and making a nuisance of himself. Any roosters I've had have usually started off with just a few crows first thing in the morning but as time goes on it has become an all-day event and at that point I had to do something about it before the official complaints started arriving. It doesn't sound like yours is being bothersome just now so I would take a wait-and-see attitude. You'd hate to get rid of one and find out later it was a girl after all.