My fiancé was called "dad" by our son for the first time a week ago. Now he can't discipline him because he's scared of losing the title.

This has been one incredibly eventful week. Last week, while home sick from school and work, our 8 year old called my new fiancé his dad for the first time.This was a big moment in our lives since my son's biological father is alive and well but too strung out on drugs to be a parent. My fiancé and I started dating while I was still pregnant and he's been acting as a parent to our son since literally before he was born. He bought diapers for our son with his entire check when we started dating. That's how involved and active he's been.All this, and he still says he never saw himself as a father or parent to Logan (son). So when Logan made it clear to Chris (fiancé) that he sees him as his father, it had an impact on Chris' parenting behaviors.Logan has been getting away with murder over the past week and Chris is usually a great disciplinarian but now he's been a pushover and Logan is definitely taking advantage. Not doing chores, misbehaving at school, talking back to me.All stuff Chris usually handles quickly and now he's letting it go.What's the best way to address this with Chris?Also, I'm pregnant. Haven't told anyone yet. Wondering, given this new development in their relationship ship as father an son, when I shoukd bring it up. via /r/Parenting http://ift.tt/2oCtpks