From: Rabbi Moshe Sofer
To: Rabbi Sender Meizlish
The daughter holding a Shtar Chatzi Zachar must prove that the assets she seeks to collect existed at the time the kinyan was executed; for assets she can verify, she collects her share, and for those she cannot, she receives nothing. The Chasam Sofer affirms this ruling on the principle of ein safek motzi midei vadai — the male heirs hold a certain claim while the daughter's entitlement remains doubtful. He further limits the Rabbeinu Meshulam principle permitting mutual acquisitions of davar shelo ba la'olam to cases where both kinyanim appear in a single document.
Source: Shu"t Chasam Sofer CM §186