The characters were in part also responsible of the failure of the Eilservs' plans with the giants in the surface. After dealing with the problems in the Vault, Eclavdra would certainly seek vengeance, directly or through proxies, for all these setbacks.
Taking advantage of this schism, the dissidents of the Vault decided to push forward their plans. Through their leader, Nilonim, they came in contact with the party, helping them leaving the Vault. They managed to do this disguised as slaves in a drow merchant caravan.
In return, the rebel leader asked them for their support in one of two important missions to the cause: 1) rescue Teregim, Nilonim's second in command and recently captured, from the dungeons of the Fane of Lolth before the priestesses have the chance to torture and question him, or 2) help Captain Eclan and his crew (Area B2/24 Encyclopaedia Subterranica) hijack the two galleys from the Fane's wharf cavern (Area 20 D3 Vault of the Drow).
"Captain Eclan has been in contact with Nilonim and together they plan an uprising in Erelhei-Cinlu. In the chaos of the uprising, they hope to lead a mass escape of slaves and other disaffected inhabitants of the Vault by way of boats and barges on the Pitchy Flow."
Encyclopaedi Subterranica p.99