Surname

[aaannndddyyy]

Adding a name and there adding a field surname, that field's content is not shown anywhere on the person's fact sheet. Only what's entered under VALUE and nickname is shown

[michelesalvador]

Yes, the name Value overrides all name pieces (Prefix, Given name, Surname prefix, Surname, Suffix).
Name pieces are intended mainly as a confirmation of the name Value. They could be used for sorting/grouping.
Therefore name pieces are displayed only in the absence of name Value.

[aaannndddyyy]

No, even with value being empty, the surname and given name are ignored