Ruling on allocating part of the estate for sponsorship of orphans
Question

                Is it permissible to allocate part of the estate for sponsoring orphans if all the heirs agree to that?.
Praise be to Allah.Undoubtedly sponsorship of 
    orphans is one of the greatest righteous deeds, and it is something good and 
    praiseworthy that Allaah has enjoined in His Book, and that our Prophet  
    (peace and blessings of Allaah be upon him) has encouraged in his Sunnah, as 
    has been explained in the answer to question no. 
    47061. 
It is permissible for the 
    heirs to allocate part of the estate for this purpose, so long as they are 
    adults of sound mind. As for a minor, it is not permissible to donate any of 
    his wealth even if he gives permission, because his permission does not 
    count. If there are minors among the heirs, it is permissible only for the 
    adults of sound mind to donate some of their own shares for sponsoring 
    orphans. 
If someone donates some of 
    the minor’s wealth, then he must pay it back to the minor from his own 
    wealth. 
It says in Sharh Muntaha 
    al-Iraadaat (2/175): It is haraam for the guardian of a minor to dispose 
    of anything except in the interests of his ward, because Allaah says 
    (interpretation of the meaning): “And come not near to the orphan’s
    property, except to improve 
    it” [al-An’aam 6:152]. If the guardian gives charity or a gift, 
    or indulges in favouritism by selling some of his ward’s property for less 
    than it is worth, or he buys something with it for more than it is worth, 
    then he is liable for what he donated or showed favouritism in. End quote. 
Shaykh Ibn ‘Uthaymeen (may 
    Allaah have mercy on him) was asked about the heirs giving up a piece of 
    land to one of their brothers so that he could build a house on it. 
He replied: If the heirs 
    are all adults of sound mind, there is nothing wrong with them giving up a 
    piece of land to one of their brothers. But if there are any minors among 
    them, it is not permissible for any of them to give up what belongs to these 
    minors, i.e., nothing should be taken from their share of the estate. But if 
    one of the adults of sound mind gives up his share to his brother, there is 
    nothing wrong with that. End quote from Fataawa Noor ‘ala al-Darb. 
And Allaah knows best.