1/4 black Caribbean, 3/4 white british baby girl

I'm white british and my other half is mixed race - white british and black Caribbean which means our little girl will be 1/4 black and 3/4 white. I would still say my little one will be mixed race ethnicity if asked on a questionnaire, but I have a friend who said "a quarter black isn't enough to count as mixed race". She is mixed race herself. I was hoping to get opinions from anyone in the same position? I want my little one to be proud of her heritage but feel like putting white is ignoring it somehow?

Also, on another sidenote, my other half isn't massively in touch with his black Caribbean family so I can't really ask them... I don't really know how best to care for afro hair if my little one gets the hair gene from her Dad. I wondered if anyone had any advice as I know it can be difficult to care for, especially with babies! I know I'm massively ahead of myself but any help would be appreciated as I'd like to be prepared.

Thanks 😊 xx