Swarm: (While attacking a squadron engaged with another squadron, you may reroll 1 die.)
Instigator: "Enemy squadrons at distance 1 are treated as if they are engaged by 2 additional squadrons, even if they are not currently engaged."
So the question is:
If I have Instigator, and he's doing his Instigator thing to a bunch of enemy squadrons, would my little lone TIE fighter get SWARM when attacking the enemy squadrons? I think so based on that wording.