We are here, we just need to know your question? If your Siamese is mating with a street cat he is doing what all unaltered cats will do. He needs to be neutered to stop this behavior, and if not needs to be confined to your house.If your cat is the female, she too, should be spayed to stop this behavior. If she is purebred you need to keep her confined to stop unwanted mixed kittens, there are way too many of them now. Please post back and ask what you need, I'll try to help!