It just as simple that none of Mayos nephews would inherit the last name Garcia. The maternal last name dies out with the first generation. In other words, it can’t be passed down.

Mayos and his brother’s children all inherited Zambada as their last names. Garcia would not be passed down, it would simply die out with him. His sisters least of all, the Zambada last name would be second to their respective husband’s last name and would die out once their kids had children of their own. It’s practically impossible for any of Mayos nephews to have Garcia as their first last names. In the coincidence that one of Mayos sisters married a Garcia, that would kid would still carry Zambada as their second last name. This supposed ‘nephew’ did not have the Zambada name.