Alright, so here's your challenge.
Have, by the 19th century, a 'Greater Iberia' movement, similar to the Scandinavian movement and/or Unification movements.
Secondly, try to not drastically change history to a point where Europe is fundamentally different, IE keep England/UK and the
national identities of the Iberians up until the movement and the various other historic European nations.
Greater Iberia being defined as what is Portugal, Spain and France.