[member="Tathra Khaeus"], I agree with certain points you bring up, however, if you put a strict limit on the writers/characters that can be involved with an invasion, Invasions are likely going to turn into the same writers involved in each and every invasion. To elaborate on what I am saying with this is that 9 times out of 10, every one of a Faction's Admins is going to be a direct contributor to the invasion, which in itself will immediately limit the number of remaining roster spots should this particular setup be pushed forward (hypothetically). So now where invasions used to bring in amorous amounts of writers to breath life into a story (no matter how disorganized of a story it is), we would be limiting that to a slim fraction of that where more times than not, it will simply fall to one Faction's admins writing with/against the opposing Faction's Admin team.
Furthermore, with your mention of "Player Characters," consideration should be given to the fact that not all "Player Characters" are primary characters. For example, until recently, this character was not, and wouldn't have been, considered a primary/story critical character - he was simply a starfighter pilot. He wasn't a commanding officer/general and wouldn't have been viewed as a kingpin in any other facet. Because of this, and I understand where you were trying to go, I just think it would be too difficult to amicably enact this without particular adverse effects in doing so. Not to mention, it would be very difficult to truly implement this proposal without a significant backlash from the community as a whole.
Just my thoughts.