Here you go https://www.emirates.com/uk/english/...icket-options/

As far as I can tell, yes you can rebook within the same region, not too sure which region Turkey falls into on EK.

The question I would ask and maybe one of the EK staffers can answer, the differance between the tickets issued before/after September seems to be you need to be booked into the same booking class. Does anyone know the reason for this, did the original policy allow people to upgrade to business from Eco or simply to stop users on cheap saver tickets getting Flex tickets? Or control revenue buy limiting fare classes and suggesting an upgrade fee if the clas is not availible?