Asking as I came up against someone who said you can.
They had 4 Xwing's, with Wedge the leader at I-6, Wedge and 2 of the other Xwing's had Swarm Tactics:
"Swarm Tactics- At the start of the engagement phase, you may choose 1 friendly ship at range 1. If you do, that ship treats its Initiative as equal to yours until the end of the round."
So with Wedge he could choose 1 of the other ships with ST on to make it I-6, then with that ship choose the other ship with ST to make that I-6, and then with that ship choose the last ship to make I-6, so therefore chaining all ships to I-6.
Is this legal, kind of feels wrong, but I can't see why it would be, so thought I'd ask here.
Thanks