Impermissibility of the heir's agent disposing of the affairs of those who did not deputize him

Q: My father died and left behind seven sons, five daughters and two wives. He bequeathed one-third of his money and made his eldest son an executor of this will. The elder brother also became the guardian of all the heirs except two of his brothers. One of these two brothers authorized the other to supervise his share in inheritance, payment of debts and alienating rights:A- Is the eldest brother permitted to act freely concerning the deceased's property in terms of alienation and sale without the presence of the other two brothers who did not authorize him to be the representative of most of the inheritors? When one of the heirs objects to the agent regarding the execution of the will considering that one-third is too much and may harm the rest of the inheritors and ask him only to give one-fifth or one-sixth, can their objection be accepted?B- If the eldest brother was authorized to take care of the affairs of the minors while they are his half-brothers/sisters and have an elder brother, then they gave him absolute power to run their affairs but the eldest brother objects to this action because he is their eldest brother, should his objection be accepted?C- The deceased had a farm and one of the inheritors wants to invest in it and another one wants to sell it. What should they do?

A: First, the eldest brother has no right to run the share of the two brothers who did not authorize him - if they are adults - without a legal proxy even if (Part No. 16; Page No. 365) he is the agent of most of the heirs. No one has the right to object to the agent as long as he acts within the limit of the one-third which the deceased bequeathed claiming that they are poor and one-third is too much. The Prophet (peace be upon him) gave permission to bequeath one third. The legal bequest should only be applied after the death of the testator. However, they have the right to object to him if he spends it in other than the legal ways of spending which the testator defined or in any act other than charitable acts if the testator did not define a way of spending. The poor relatives of the testator are worthier to take the one third in order to fulfill their needs after paying for Al-Mu`ayyanat (definite ways of spending) which the testator defined. Second, if the ruler appoints the eldest brother who is not a full brother, as guardian of the minors while knowing that they have a full brother, the half-brother does not have the right to object to the guardian. If the judge appoints the half brother and does not know that there is a full brother, the full brother may submit his case to the judge and explain the matter to him and he will judge according to the best interest of the minors. If the minors themselves authorize the eldest brother, their authorization is not valid and it is the judge's decision to appoint a guardian over them if their father did not assign one. Third, if the father has a farm and the heirs differ about whether to invest or (Part No. 16; Page No. 366) sell it, they may share it if it is possible and each of them can run his share as he sees fit. The one who is entrusted with the shares of the minors has the right to run them as he sees is in their best interest. If it can not be shared, they may sell it and share its price. If they disagree, they should resort to the court to settle this dispute. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.