Spanish law is specific here: the route is for descendants of the Jewish community expelled from Spain in 1492, not for Jewish ancestry generally and not for Spanish ancestry generally. What counts as evidence is a certificate from a recognised Jewish community or rabbinical authority, family use of Ladino or Haketía, a ketubah following the Castilian tradition, or an expert report on your surnames — weighed together rather than as a checklist. Surnames on their own are the weakest of these and the most often oversold.