Maybe I'm the only one, but I definitely went through some crazy emotions when my DP and I first got together and I became a part of DP and DSS's life together – feelings came up that I was shocked and horrified that I was feeling.
I felt resentment, irritation, anger, sadness, insecurity... old wounds from my own childhood opened up, I doubted my importance to my partner when I saw how close he was to his son, I was scared of not being 'enough' to DSS... none of which I saw coming, none of which I could control to begin with, and none of which I knew how to deal with.
DSS is a wonderful kid, and he made my life so much easier than so many step-parents have it, and it's still taken us a while to navigate our relationships with three of us in the picture when it was the two of them against the world for so long.
And because they were so close, and because I was so ashamed of having these feelings I seemed to have no control over, I was terrified of talking about how I felt with my DP. I was angry with myself for feeling how I was feeling, frustrated and ashamed that I had to keep taking myself into the other room to get my emotions under control, and I felt very alone in dealing with it all.
I don't think the wife in this situation is handling any of it very well, and should absolutely be keeping her actions in check around her DSD, and I'd also hope that she's be granted the time and opportunity to work through her feelings the way I had to.
It took me a good couple of years to get my heart fully in check and feel secure with my place in our home, and to build up a relationship with my DSS that I truly cherish now.
We can't always control how we feel, and if you've chosen to share your life with someone, sometimes you're going to have to support them through emotions you wish you didn't have to support them through.
That goes for both your wife's emotions and your daughter's.
None of this is to say that banning the OP's DD from staying overnight or speaking in a negative way about her is OK – it's absolutely not.
But I do know how it feels to be desperately wrestling with your own emotions in a way that makes you behave in ways you don't recognise or like, and I can't help but wonder if this might be some of what's going on.
If you talk to your wife and she's not feeling like this at all and I'm way off and she's just being mean, fine, absolutely do what you need to do to protect your daughter.
But I have a hunch it may be worth a heartfelt, supportive conversation. Just to see.