The only way to expand iberian wolf territory, or any other wolf territory in mainland Europe, is to safeguard their existence in such territory. Local people must accept them and legal/illegal killings cant be higher then number of cubs born. Yes, more protected parks would help here.
Introduction of captive stock is a big nonsense (only the UK would need human help in introducing wolves). Wolves have many cubs per litter and youngsters leaving packs travel large distances to find a new territory, easily over 1000 km. An established population, when well protected, will grow quickly and exponentially till they reach saturation.