The premise for this event is a bit off, Bretonia isn't looking to shoot people leaving Gran Canaria, they're just annexing the system, if anyone wants to run away there is no need nor desire to stop them.
You would have to make it a simple "let's stop the invasion" type brawl instead, though not that many Zoners are really wanting to roleplay this, there is no reason to attack Zoners otherwise as mentioned.