Congrats, and coming from my perspective (I am parentless, and have been since I was a child), all I can say is you are doing the right thing!!!!! I have wonderful in-laws who treat me like their own, and it's wonderful!!!!! I am glad you like her, and accept her. I've had situations where parents didn't want me around...not from the right background I suppose.
I wish your son and his DBTB (dear bride-to-be) all the best for a very happy future together!