The one you referred to, which I assume were Arcachon and Arcaea. Caerwyn and Astrum/SA. And so on.
And Arcaea and Ethiala. And Arcaea and Greater Aenilia. And, heck, Arcaea and Soliferum, Arcaea and Mosesadelphia.
And
permanent vassalage doesn't work. There has to be some way for the center of the empire or whatever to change, which is what I started moving toward (and Velax has continued) on the FEI.
