Is this quite as straight forward as everyone seems to think?
I assume you have a contract and that will specify your pay/terms and conditions (I would imagine).
Any company can change these at will and offer them to new joiners but I would be surprised if they could force them upon existing employees.
They could get rid of you and then ask you to reapply (as an FO) but wouldn't that attract some sort of redundancy?
I have no experience of this sort of thing - just some obsevations from an unqualified observer...
