I was thinking in the son, because the father already ruled from 1923 to 1929. But if you need a truly strong and democratic Spain, here is what I think is the best idea:
All begins in 1833 with the
First Charlist War, more exactly in 1837: The Royal Expedition of the Charlists has reached the walls of an unprotected Madrid Just at the same time that another Charlist army arrived from the north. Two rebel armies stand in front of Mari and the closest Liberal army is five days in the rear of the Expedition. Because unknown reasons, Charles (the absolutist pretender) did not took the city and fled back to Charlist territory. Not in TTL.
In TTL Madrid fell to the rebels, Elizabeth II and his mother, the regent, are captured and forced to abdicated to Charles, who now is Charles V. Some time after, absolutism has returned to Spain, liberals went underground and Charles V helped the absolutist king Miguel I of Portugal to regain the throne. Both countries are now ruled by absolutists. Some decades after, the liberals, crushed under the boots of absolutism, have become more and more radicals, wanting nothing less than a republic. Moreover, the common persecution of both Spanish and Portuguese liberals has made them to forget their differents and join forces in a common front. In 1868, the 30 years of political inestability (including numerous liberal military coups and some open rebelions), coupled with an economic crisis and the declining health of the Spanish king John III, cause the ignition of the "Glorious Revolution", which succesfully defeat the absolutists first in Spain and then in Portugal. Shortly after, the victors, influenced by the recent foundation of Italy, proclaim the Federal Republic of Iberia, thus achieving the political unification of the Iberian Peninsula.
Iberia would face her own challenges, such as the Worker Movement, colonial wars, political crises and such, but overall, she will survive.
If you like this idea, we can expand it to fit with this mod.
