Wow, there needs to be a serious intervention or you need to keep your child separated from SD.

Seriously, keep on waiting around for your fiance to do something & your daughter could end up seriously injured.

I lived this at an older age SD was 10 MY daughter was 7. It went on for years until SD went to far physically at 11 and I had to put her out of my house and she could not return until she was in some kind of medical counseling treatment to deal with her obvious issues.

She left never got treatment I allowed her back in treatment at 15 and she did the same exact thing except she went after my other daughter a quite easy teenager that she thought she was going to command. And the abuse that her own bio sister has endured is beyond measurable. When younger SD who was 14 last summer came to visit I advised DH that SDbully had 3 shots if I caught her bullying her bio sister once I would advise him and he could handle it, twice and he could handle it, the third time I catch her I was becoming UNdisengaged and her ass was as good as mone.

The first time I caught her DH dealt with it, the second time DH dealt with it, and when he returned into my sight I told him. Next time her ass is mine...she moved out the next day...take care of this now

Once or twice, I could see that happening, until you notice that there's a pattern of behavior. You see how your SO/DH deals with it. Good thing to notice since you're thinking of a life together.... But, come the 3rd time, and you aren't being proactive in your own child's defense??? Why?

I don't know if you're living together? If you are, I would not be living with him and your child. He isn't responding to his child's actions. Which means there will probably always be a set of different standards for each of your children. He will expect a higher set for your child and his will do no wrong. Or his will do wrong but do nothing about it.

I'd tell him that you will not be marrying him until you see a change in his lack of parenting. Your child's welfare is at stake and how she will be raised.

Agree with the other posters. His lack of dealing with it is a window into how it will be from now on. As SD gets older she will be able to inflict more harm.

I'm sure you received the " Well I didn't SEE her do it" from biodad (translation: I will
ALWAYS,ALWAYS,ALWAYS believe my flesh and blood over you and your children--even if I see her horrid behavior with my own two lying eyes, I will never hold my bios accountable for ANYHING!)

We've had SMs on this site who LITERALLY caught skids on video, stealing, lying, desecrating, damaging, pillaging and inflicting harm on others. They show the vid to biodad and get a host of lame excuses, finishing up with: "Why are you spying on MY child" and "You just (hate my child)/ (are jealous of my child"