Section 1085 ABGB provides that use of the property and use of the money are set off against each other when the contract is dissolved. The unwinding must therefore address who used the property, which benefits were drawn and how the purchase price is returned or accounted for.
For improvements and deterioration, the buyer is treated as a bona fide possessor under the statute. That standard does not answer every detail of the final amount. Works, damage, running costs and changes should be recorded with invoices, photographs and a joint condition report.
Unwinding the first purchase and contracting with the later buyer are separate steps. Price, possession, land register, release of encumbrances, taxes and escrow must be coordinated. Treating the two transactions as one automatic process creates additional risk.