Newbie Question about It Kills With Fire GC quest

Hi guys. Recently returned player with a baby question you're probably all sick of (I couldn't find the answer on Eorzeapedia or anything, though).

Can you do the final phase of this with members of other GCs if they've completed all the steps leading up to the final battle in their respective flavor of the quest? I.e. if someone from Adder's has done all the NMs, etc., and is ready for Bowl of Embers can they team up with someone from Maelstrom who's done all NMs, etc., and ready for Bowl of Embers?

Thanks!

Yes. The only bonus you get for doing it with all from the same company is an extra 500 seals, I think.