Splitting Balmung and Gilgamesh up on data centers is probably the best fast solution. But moving one of them or the other to Primal or Chaos will only break that data center. They need to create a new data center and redistribute all the servers. The best solution would be to create a new world for Balmung and Gilgamesh and create an option for free companies to transfer to the new server, preserving all states of their free company and housing. When the FC moves, the players would be given the option to move server or stay. This option would only be for splitting up servers.