Cats are notorious for showing very little allegiance to their owners/feeders. We often wonder where our Freddie spends his days.
When we lived in Brighton we had a visiting cat that we named Thomas. He would enter via the cat flap (we didn't have our own cat at the time), and he would spend his days with us. We neither fed nor encouraged him.
In those days we used to drive down to France a lot; our house here was always beckoning. Our only problem was Thomas who came to rely on us more and more. We didn't want him to just wander around the house for the several weeks whilst we were away, nor did we really want to lock the cat flap to keep him out.
We began to suspect that he had previously belonged to people who had moved away, and that he had become an abandoned multi-ownership cat; one of whom was us. Eventually we began to feed him as he always seemed hungry.
Eventually Lady M (Mumsy above) even considered bringing him over to France, but we had no idea who his other carers were; they might have been children, so the idea was instantly shelved.
Above was how I imagined her passing through the customs. It was just an idea!