Originally Posted by Zhaboka
No; I took Mandalore and HK-47 with me to Onderon in the Basilisk. Kavar walks out, says "This ends here, Vaklu!", stuns the soldiers, and then has his I-won't-answer-your-questions dialogue with the Exile. As soon as he and the PC begin to fight, Mandalore and HK disappear from my party and I'm fighting him solo.
That's probably the issue. Kreia's appearance on Onderon is vital, and normally you don't have a choice in not taking her.