When I met my girlfriend she had a 5 year old son. We have been together for years now and I consider him as my own child. 
That is so sweet.  I really commend people who treat kids like their own, it's so important for a kid to grow up feeling like they have a lot of people in their corner.  I have a stepdaughter myself.
You know then how it feels to have a child that is not your own yet accept them and love them unconditionally. You're awesome!
Yes, it's true in life too when you grow up, sometimes the best family has nothing to do with blood relations.