Hi....for whats it's worth.
We had a small cat hanging around in the summer. I fed him/her and gradually gained his confidence. I began to realize he was a feral cat. I started to worry as the nights got colder. I rented a trap from the Humane Society but could not entice it in. The cat is still around, even in -30. Where it goes at night I don't know. As I type it's sitting on the hood ( bonnet ) of a neighbours car who just drove in. What I'm getting at is that cats are incredibly smart and resourceful. Keep the faith.