Appropriate way to refer to a child of colour in a fic set in the near future?

This is an odd one, but I don't have anybody I know personally who I can ask. I'm writing a fic set in the near future (think within the next 5-10 years at the outside), in which two Caucasian men in the US have adopted a couple of kids. One of said kids is black/white biracial, and I want to make a reference to how time has passed by pointing out how her adoptive grandfather on one side has mellowed and become more accepting since his son's marriage to his partner and adoption of the little one, which by necessity is going to require bringing up that she and her daddies are not the same race.

This truly is a little-going-on-outright-nitpicky-paranoid detail, but I'd rather not inadvertently step on a bunch of toes, so could some little_details members of colour tell me if you'd find it offensive or in some way inappropriate for me to refer to said little girl as having "melted-chocolate skin" instead of just saying "she's black"? Up until yesterday I wouldn't have thought anything of it because my thought process was "everybody knows what colour melted milk chocolate is, chocolate is sweet, I don't want to steal 'coffee-and-cream babies' from Neil Gaiman because I want something more directly relatable to children, there's a nice subconscious metaphor about her being a sweet child in there," but then I found out Cadbury is getting their confectionary behind sued off for comparing an African-American model's skin to chocolate, and I kind of went "shite, I do not want this to become known as 'the story where Nina proves she grew up in deepest, whitest suburbia and couldn't be arsed to check if this is okay'."

Anybody feel like weighing in and saving me from myself? :S