EDIT: nm, not a bug, don't know why it took so long though. I'll leave the 'interesting' story below.
hmm, I'm not sure if this is a bug or not. In the game I'm playing, I founded the Empyrean and founded the Overcouncil, but then in order to go to war with the Khazad, I had to change membership from overcouncil to none. However it was after me and the Khazad tried to vote on a council leader, but it came out a tie (greedy dwarves voted for themselves, figures...). Then I later went to war with them. Long story short, after the war, I went back into the council and got the other two civs into it, but this has been for several turns and no popup relating to the overcouncil has come up yet.
Anyways, I should have accepted the Khazad's deal for bieng my vassal because I ended up in a really long drawn out war of attrition which I won...... eventually, lol >< Having no siege capabilities, the Ljossafar certainly aren't good at war. The fact that he only had 3 cities and I had like 5 and he was squeezed into a corner of the continent probably helped, plus the fact that I had built up troops on the border.
Still, if he had been about the same size as I am, or larger, I'm not sure how long I would have lasted.