Gaming is for having fun. Fun requires clear rules.
There is an order to it, though usually it doesn't matter:
1) Resolve all combat between ships in all hexes and draw reputation
2) If you have a ship in a hex with another players population, attack population cubes
3) If you have a ship in a hex with another player's disk and no population, remove the disk from the hex
4) You may place a disk in any hex that you have a ship with no disk
So if you have no disks left on your track and another player takes over one of your hexes, you can place that disk in another hex in the same round.
He was asking about order in last point.
There is no order specified.