New Pet?

So a few weeks ago me and Karson were coming home from church and there was this kitten that was in our front yard. She was very skiddish but Karson kept trying to pet her. He finally did and she really warmed up to hime fast. I got Karson in the house and told him to leave the cat alone. Several hours later we heard a meowing sound and that kitten was still sitting outside our front door. It had started to snow and we didnt know what to do about this kitten. We put a little bed out for it and it slept there all night. We didnt want to feed it because we really did not want it to stick around. We already have a cat and one is just great for us right now. It stuck around for the next couple of days and then the temp started to get really low so we let her sleep in the garage and we did end up feeding her. Well lets just say that now we kind of have a second cat. We now bring her in at night to sleep and then she is outside all day long. We kind of hope she wonders off and doesnt come back but what do you do. She is really sweet and loves the kids and they love her. We have named her Abby and we will just have to see what becomes of her.