In this study, published in 2008 in the law journal Digesta (p. 159 ff.), the impact of the promisee's contributory fault on a genuine contract in favor of a third party is examined when the promisor breaches their contractual obligations, resulting in damage to the third party. Contrary to the prevailing view, the study argues that the promisee should be treated like any other person regarding the effect of their fault on the third party's legal position. Therefore, only if the promisee’s conduct is attributable to the third party under general legal principles can the third party's compensation claim against the promisor be reduced under Article 300 of the Civil Code.
You can find the study (in Greek) at the link below.
Contributory fault of the promisee in a genuine contract in favor of a third party