Complex sentence: Accepted modern terms in the United States for people of mixed ancestry include "multiracial" and "biracial", however these include other racial mixtures and it is still the formal register one specific to the black-white mixture.
Split into simpler sentences: Accepted modern terms in the United States for people of mixed ancestry include "multiracial" and "biracial". However, these include other racial mixtures and it is still the formal register specific to a black-white mixture.