Thanks, everyone, I eventually got past this by separating Laeral and having her rile the goblins solo and draw them towards the bridge that leads to the main entrance, There, I had her and my drow cleric tank the melee goblins and keep them away from Astarion and Gale, who spoinked at the casters and archers while tossing grease, oil, and fire at the entrance where they had collected.
I would have preferred not to have killed any of them, but they got in the way.....
