Is it permissible to indirectly use sales contracts signed by relatives to recover the remaining price of the mother's share in a land that was forcibly sold for less than the agreed-upon price and market value, along with a due compensation amount, in addition to the price of the grandfather's brothers' share who were deprived of inheritance due to adoption, knowing that the buyer exploited the dispute and the relatives' evasion?

Compensation for false testimony is not permissible if the damage is only moral. It is permissible if it results in the payment of a sum of money or the loss of a financial right. The sale of real estate under duress is not valid, and the land remains the property of its owners. However, if the sale was made without duress, then the sale is valid. Your grandfather's siblings have the right to demand the annulment of the contract and the reclamation of their share if they were disinherited due to the adopted child, or they can demand the price of their share from whoever took the price of the land.