About 4 months ago one of our gray Australorps went missing. We had 2 gray and 4 black Australorps. This morning I was out feeding the girls and guess who showed up. Now I know someone has been taking care of this girl because she looked to be in fair shape. A bit ruffled and not as good looking...
At the very least you need to tell all your neighbors that the chickens and rooster they are seeing are not yours but hers. If Jane won’t control her flock and you don’t talk to her about it then you probably have to live with it until she moves.