From: Rabbi Moshe Sofer
To: Rabbi Lipman
The Chasam Sofer rules that a guardian is forbidden to use a minor son's 200 gold coins (proceeds from the sale of estate property) to fund a daughter's dowry, since daughters' maintenance and dowry rights attach only to the father's actual estate assets, not to substitute proceeds. He also engages the Rambam's position that a loan acquires in a sale, distinguishing it from kiddushin by showing that the derivation of kinyan kesef for kiddushin requires actual money, while for sales the verse permits loans.
Source: Shu"t Chasam Sofer EH I §127