As the "plaintiff" here, I think you know where my biases lie. That said, I present another quote from the Kabrinskia case:
It is currently through a bug that realm mergers with the last duchy containing the capital can join another realm by 'pushing a button'. Even so, any merger of an entire realm by its original conception whether it is by by pushing a button or through the friendly takeover of all its regions outside of a war is not allowed.
Gretchew, Saffalore = "pushing a button"
Chateau Saffalore = "friendly takeover outside of a war"
I would suppose - without knowing - that "war" here refers to a previously active war with IC reasons, and not just mechanics-based declarations of war, because those are always necessary to TO a region and thus "takeover outside of a war" by that definition would be impossible.
