Name change

[monicaregister]

A friend of mine whos also from el salvador has a name and surname in spanish. Shes also mestizo, but what doesnt make sense is this. If shes biracial, then why does she have a european name if shes not 100% european then? What happened to the other half? Like 1000 years ago the only people living in el salvador were native americans and they didnt speak spanish and were instead speaking nahuatl, lenca, maybe quiche, ect... If someone is biracial and yet have a european name and surname, what happened to the other half? If theyre biracial, then who were their relatives like 700 years ago if native americans were the only ones in el salvador and european settlers from spain had not come yet to el salvador until 1524? 700 years ago it would have been 1321. She wants to legally change her entire name to what her ancestors were like 700 years ago because she believes that they were originally native americans but doesnt know in what language their names were originally in? Nahuatl, lenca, quiche, ect... If not genealogists, then who can help her with this??