She definitely can not pass for entirely Polish, but her last name is a sure sign of her Polish heritage! I tend to believe that identifying as only Polish or only Black may not happen, since her framework (that is, what we teach her) won't allow for that. I'm sure she will come into contact with people who will want her to call herself Black, because she has a black mother (I doubt that any who would encourage her to identify as only Polish, since that's not "allowed"). I would hope that she would resist. Otherwise, we would be having some serious debates!
I have some evidence of how that framework has played out in the examples of my three youngest siblings. They are Black and Italian, and they identify as such (sometimes biracial, sometimes African Italian-American). If someone tries to call them either one or the other, they correct them. They see it the way I do. And it's quite simple. Mom's black, dad's Italian. So they are Black Italians. If both parents were Italians, that's what they would be. If both were Black, that's what they would be. It's not really something that you can choose. You can deny, but that would not change what you really are. And, of course, it doesn't make for who you are.