Key legal question
Whether the sale was invalid for prohibited double representation by the broker C.
Extracted holding
The challenged sale was not invalidated. Even assuming double representation, the seller had seen the draft and authorized the broker by power of attorney; the conflict-of-interest risk was excluded and later ratified.
Extracted reasoning
The broker was only an intermediary and did not bind the buyer. Swiss case law allows an exception to the prohibition of self-dealing/double representation when the represented party is sufficiently protected, particularly through prior authorization or later ratification and absence of real conflict risk.