I really am surprised you guys in Spain are allowed by your CAA/Companies to permit ad-hoc jumpseat pax and that you as Pilots are happy to so so. Someone could easliy forge a crew ID and Licence and gain access to your flightdeck with possible terrible consequences. Most other airlines in the EU require authorization from Ops before granting such a request and even then only certain categories of individuals are permitted, failure to adhere to these rules will result in dismissal for gross misconduct and quite rightly so imho.