From: Rabbi Moshe Sofer
To: Rabbi Shlomo Zalman
Even accepting the father's claim that his daughter's refusal constitutes ones, the Chasam Sofer rules it is absolutely forbidden for him to provide a dowry for a second match while the first engagement remains unresolved. Since the dowry is entirely in the father's control, his willingness to fund a second match exposes his claimed helplessness as hollow. The court should impose an active cherem barring him from assisting with any new marriage until either the daughter proves justified cause before beis din or the first groom forgives the breach.
Source: Shu"t Chasam Sofer EH I §114