You cannot fly a Spanish registered aircraft unless you have a Spanish passport. How would transferring Iberia pilots to BA (no restriction on nationality) be considered fair is the reverse is impossible.
Spanish protectionism at its best, part of the root cause (as well as ostrich impressions) of their current problems.
For example, Iberia long haul pilots require a brand new set of jeppensen plates with the route highlighted on them at the start of each briefing. BA pilots print their own briefing material and the plates are stored on the a/c and are reused until they are out of date.
How many other ridiculous costly working practices do Iberia have.
BA pilots voted to accept a pay cut and increased productivity at the start of the financial crisis. Iberia?
I suspect most Iberia pilots would be shocked at how hard BA pilots work. I suspect the comparison could be made for most departments.
Stop looking over the fence, blaming others and FIX YOUR OWN PROBLEMS, or you could end up like Alitalia.