[member="Barr Vexos"] [member="Allyson Locke"] [member="Arisa Yune"]
Not dead, just resting!
As Ally said, historically the SIS hasn't had a ton of exclusive threads, they are more a tool/category we use in other Alliance threads whenever we want to do spy type things. The group does have a leader, at least OOC, which is [member="Aela Talith"], though like the rest of us her involvement ebbs and flows.
We've always (at least I have) written agents as operating more or less on their own, so you are absolutely fine to just RP an agent in more general GA threads like some others already do, but I also don't think the idea of an SIS themed faction thread is a bad idea at all!