*puts on flame-retardant suit*
How is this any different from Solaria handing over all but one of its regions to Luria Nova?
a) Given that that situation was, in fact, ruled as an illegal realm merger, and those involved punished, I'm not sure what this question is meant to accomplish.
b) That was actually a two-part process, with the initial merger of most of Solaria's regions into Luria Nova (sans the Duchy of Courts of Stone) being far from a total realm merger. It was only the bug that allowed Sevastian to join his Duchy with LN, despite it being the last Duchy of the realm, that caused the
second stage of that to be a true realm merger.
