Just reached the point on Telos when the Ithorians need rescuing from merc's

and my party has disappeared - Atton and Kreia are still in my party members list in the inventory, but I can only control my PC. Not sure if this is a bug or I'm meant to take on the mercs on my own? I'm pretty sure not, as I hear Kreia say "Lets end this" partway through the battle?

Any idea? Thanks!

Its a bug.
Just re-add them to your party again, they should show up. It's a pain because you lose them after helping Chobo with the droid, then they sometimes get "Lost" on their way back.
Just remove and re-add them, should clear it up.

Thanks a lot, worked when I tried it - makes the merc battle a bit easier!!