My DH and I have been married 1.5yrs but have lived together for 2.5. He has SD8 and together we have a 7mo son. We were cautious in the beginning of our relationship. I didn't spend the night if SD was with him (until I moved in after we got engaged) and didn't assume any kind of parental role until I moved in. When I moved in, however, I became the "mom at dad's house."