Our daughter is mixed.
Back when we were married this was still a problem for some people on my husbands side of the family.. One of his aunts admitted my inlaws did not expect our marriage to last because of it. One of his grandmothers was still using the N word and called Hispanics Wetbacks, even though our families had been here longer than her families.
Our daughter probably did not notice for a long time.. This is all "her normal" life, so it did not make a difference. She was too young to understand.. But it was interesting to see people expressions when they had only seen my husband with her.. and then I show up and they put it all together..
My family is Mexican American.. My husbands family Anglo.. they do not embrace their German heritage in any way. They never refer to it or have any traditions.. etc.
But my family speaks Spanish and cook our family recipes.. etc. We explain how our ancestors were her in Texas when it was still Mexico..
Again in today's world, over all it does not make a difference, but when our daughter attended college, she and a group of other girls started a group for students of mixed ancestors..
Very interesting combinations and not really more of one race than another.
They spoke about how they identify themselves.. is it based on how they look, or who the mother is or the father>? The family they spent the most time with?
Soon they feel they will not be stating ethnicity, because everybody is going to be mixed in some way.
Ask a teen to describe their friends and very few will tell you, their ethnicity.. instead they will tell you , "oh she is real athletic, but plays in the band and lives over there.". Or "he is pretty shy , Geeky, but really funny when you get to know him.". They will not mention color or race, because it will not matter.
Teach her about her heritage and stories from your family history and any other languages you all know.. This will help her be her own individual.