From: Rabbi Moshe Sofer
To: Unknown recipient
A yevamah who secretly married a stranger now needs her status resolved. The Chasam Sofer rules that every effort must be made to obtain a get from the current husband before chalitzah, including financial inducements. If a get is absolutely unobtainable, chalitzah may be performed based on a triple doubt: the majority view that chalitzah is unnecessary when both parties acknowledge the marriage, the Rambam's position that kiddushin does not take effect on a yevamah la'shuk, and the Beis Meir's argument that nissu'in dissolves the levirate bond entirely. In any case, she must first separate to the yavam's community and observe the ninety-two-day waiting period before chalitzah is performed.
Source: Shu"t Chasam Sofer EH II §76