As most you know my point of collection is Spanish Legion, but sometimes I touch other places I Would not.
Think when I joined Spanish Foreign Legion at least 50% troop had previous experience in any othes army even navy units, so there were old soldiers from coe, marines, paras, etc..
Of course officers and recently subofficers also came from other units aswell, cause in 1990 Spanish Legion inner formation for subofficers and officers had been suppressed.
Many things and many stories about that to tell. Anarchy for field equipment was served.