[The ruling on al-shamlan (comprehensive assumption) for oneself, one’s children, and the tribe]

Question: Among what occurs nowadays and in earlier times in agreements or sales contracts, or in a reconciliation agreement, or in an undertaking, or the like, is that the elder of the household, who acts on their behalf, or the chief of the tribe, or the wise man of the household, attends and states that he is “comprehensive” (shāmil) for himself and his brothers or his household or his tribe; and likewise the other party. Custom has run on acting according to this shamlan and obliging (by) it. Is this permissible, and may the judge rule on its basis?