Upon returning to Vault 13, the Vault Dweller will discover many upset citizens. Interacting with any of the upset vault dwellers on level 2 and mentioning that the quest is not going well will spur them to mention that there is a movement to leave the vault. They will then tell the Vault Dweller that the faction's meetings take place at 17:00 in Theresa's room.
Theresa can be confronted at any time. Convincing her to remain in the vault requires an Intelligence of 6 and a Speech challenge, and there is only one chance to do so.