1) He himself was a born prince
2) He settled permanently in his wife's native land
As it was, both daughters of King Alfonso XII married men who qualified (Prince Carlo of Bourbon-Two Sicilies and Prince Ferdinand of Bavaria). Accordingly, both were granted the title Infante of Spain (but not the style of Royal Highness, since they already had that). Both Infantas (Maria de las Mercedes and Maria Teresa) retained their succession rights and transmitted them to their children.
Is this correct? What about PORTUGAL? Did the same rules apply there? Was there such a thing as a Portuguese Infante by Grace?