A goblet of Colovian Brandy can be received from Brelas, which is used to bribe Razelan to make a scene in front of the other party guests. Doing so allows the Dragonborn to sneak into the backrooms with Malborn and retrieve their gear, in order to fully scout the Embassy in search of information on the Dragon Crisis.
Alternatively, the Dragonborn can tell Brelas they will convince Erikur to stop his advances on her. When talking to Erikur, if he is told that Brelas wishes to meet him in his chambers after the party or that she does not want his company, he confronts her directly, causing a distraction sufficient enough for Malborn and the Dragonborn to escape the party.
Either way, she will be condemned to the interrogation room, where she can be freed later.
If she becomes imprisoned and later successfully rescued, she can be found with Malborn in the New Gnisis Cornerclub in Windhelm. She will stay there until Malborn's quest is complete, where she will follow him to Morrowind. If she makes it to the Decree of Monument at Refugees' Rest she will disappear from the game. However, if there are creatures along the way, she will most likely perish on her journey.