Thank you.
I believe that the Princess' husbands are styled 'His Excellency' and their children are styled 'His/Her Excellency'. This is unusual. Of course, under, say, English law, a child would derive his/her title from their father. If, indeed, Jaime and Inaki do not actually hold the ducal titles, then why are their children 'His/Her Excellency'?
Has it always been the case in Spain that when an Infanta married a man with not title on his own the childrenwere given titles?
Lastly, I believe that Prince Ferdinand of Bavaria, husband of Infanta Maria Theresa, daughter of Alfonso XII, was given the style 'Prince of Spain'. Was this only because his mother had been an Infanta too? Was this never considered for Jaime and Inaki?