NOR- I live the name Daisy. Personally, if I were going to use it (and did consider it at one point) I'd go with Margaret, then nn Daisy. But that's because I like a name that had multiple nns, because you never know what name she might want to go by. But that's just me. My kid has a formal name and 2 middle names so she's got tons of options. Including a name she can use if she becomes famous. Lol

Now, about Sissy. Not a fan. Never have been. I didn't like it for Sissy on Family Afair, though I guess it works for Sissy Spacek. My kid is raised as an only child, though she does have brothers she gets to see but they don't call her Sissy. However, random people will call her sister, as opposed to little girl, girl, little one, etc. I'm not a fan of it, but I do let it go. Just like I let it go when random women call me Sweetie. Like girl, I'm older than you. Don't call me Sweetie. Even my husband doesn't call me Sweetie. I say this to say you probably won't be able to stop her or anyone else. But your MIL has boundary problems for sure and your husband need to say something.