i believe there is NO solution that would keep everybody happy, Unless they set-up a seniority system with a career progress like the major EU or American companies have. Where EVERYBODY follows a career progress, and they don't change the rules every time there is a different management.
Seswa, what you just mentioned is great, that is the current policy in ALL world major airlines, unfortunately, that was QA policy also till last September when the "new management" changed the fleet transfer policy.
I believe that QA WILL eventually revert to the original fleet transfer policy with few exceptions for the type rated experienced pilots.
You also spoke the truth when you mentioned the unfair MFF policy of the 330 pilots don't want to fly 320! While 320 pilots are forced to fly both types!
It will be only useful when everyone flies both types as a completely mixed roster, or back to the sigle fleet policy (again like major airlnes cancelled it before..e.g. Lufthansa, Swiss, Etihad)
It is cheaper to learn from other's mistakes, instead of repeating them.