Iberia, being a member of IATA, section 1.3.2.2(a) of Resolution 700 presumably applies, viz:
1.3 ACCEPTANCE
1.3.1 General
Subject to the rules and conditions of this Resolution, Members shall participate in interline transactions concerning the carriage of incapacitated passengers. Members shall ensure that each interline Member participating in the transportation has specifically agreed to participate in the carriage of such Passenger.
1.3.2 Exceptions
Notwithstanding 1.3.1, Members:
1.3.2.1 may refuse to carry or continue to carry persons:
1.3.2.1(a) whose carriage because of their physical or medical conditions, on the basis of established facts, could pose a threat to the safety of other passengers and their property, the aircraft or the crew; and/or
1.3.2.1(b) who refuse to, or do not submit themselves to the specific conditions of carriage required by the Member(s)’ regulations;
1.3.2.2 may refuse to engage in interline transactions for carriage, or to commence/continue interline transportation of incapacitated persons:
1.3.2.2(a) whose conduct, status, mental or physical condition is determined by the Member to be such as to render them incapable of assisting in their evacuation of the aircraft (e.g.persons travelling in a stretcher or incubator, persons with severe mobility impairment, persons with severe hearing and vision impairment) unless they are accompanied by an escort who will be responsible for them and their needs on enplaning and deplaning during flight, and during emergency evacuation.
Not
CAA but equally, not
don't exist either.