Participating offensively, directly or indirectly, in a siege with an ID not explicitly stated as attacker in the Siege Declaration thread is not allowed.
Nothing stop players from logging, let's say, nomad dreadnoughts to mop up a pob's defense and then re-log with their proper """in-rp""" siege ships, or participating with unrelated factions, therefore effectively bypassing any in-rp justification. Also, this line stops factions that has nothing to do with the siege from participating - as it should be.
I can cheat this system with this example:
Declare a justified siege on my faction with cruiser access at most -> defenders log -> I log faction with dreadnought access, completely unrelated to the first justification -> I mop up the defenders -> I log the first faction and finish the base off.
another suggestion:
Valid Siege Declarations on a base that is already under siege will have their two weeks time period expire at the same time as the oldest valid Siege Declaration.
this line stops players from extending the siege declaration past the intended two week period.