The fact that Terran was at war, and on the verge of destruction, is what makes this NOT a friendly merger. It is a couple lords fleeing a dying realm to join a third party. If you want to deny that, then what you are doing is declaring that lords are no longer allowed to leave a dying realm, that they are forced to stick it out until the end.
A friendly merger would be two realms, in the absence of any external pressure, joining together as equals to make one larger realm. That is definitely not the case here. The fragments of the realm that used to be Terran are being absorbed by D'Hara in order to escape a losing war they cannot possibly win.
