Is it incumbent upon a woman who performed Umrah on her own behalf and on behalf of others to shorten from each braid a fingertip-length for each person for whom she performed Umrah, or is it sufficient to shorten a single fingertip-length from her braid for everyone?

It is permissible for a woman to perform Umrah (definition) on behalf of another, provided that she has already performed Umrah for herself, and that the person for whom Umrah is being performed is either deceased or alive and physically incapacitated, with their permission. It is not permissible for her to share the Umrah she has consecrated for herself with anyone else, nor to share in an Umrah consecrated for another. If a woman has performed her Umrah and exited the state of ihram (definition), and then wishes to perform Umrah for another, she must go to the hill (area outside the Haram (definition) boundary) and enter ihram anew, perform the Umrah completely, and exit ihram by cutting her hair; what she cut in the previous Umrah is not sufficient. Every Umrah is an independent act of worship. As for the intention of sharing in the reward and merit, there is no objection to that according to some scholars, and she would exit ihram once. However, the practice of the righteous predecessors was not to share the reward of acts of obedience with others.