Originally Posted by
sbams
You can only use the FF number which is associated with the passenger named in the reservation. So unless you have 2 (?) then you can not just change it to another.
There is no limit to the number of frequent flyer programme memberships you can have - though you are not allowed to hold more than one account in any particular programme, and it usually makes little sense to have more than one active membership per alliance.
However...there are probably a lot of newly-minted Alitalia status customers out there who will want to change their FFP details for forthcoming KL travel in order to obtain the free luggage allowance. I'm one of them!