Is it permissible to change the intention of Hajj on behalf of an unspecified person to a specific person, after entering into a state of Ihram from the Miqat without prior designation?

The jurists differed concerning indefinite ihram. The Hanbalis are of the view that it is for oneself. However, the Hanafis, the Shafi'is, Al-Qadi, and Abu al-Khattab from the Hanbalis are of the view that it is valid on behalf of another, provided that the designation occurs before commencing the rites of Hajj (circumambulation, sa'i, standing at Arafat). If he does not designate, the Hajj is for himself. And if he performs ihram on behalf of two people, it is for himself by consensus. If two individuals hire a person to perform Hajj, and he performs ihram on behalf of one of them without designation, he may assign it to whomever he wishes before engaging in the rites of Hajj. If the pilgrim designates for whom he is performing Hajj before commencing the tawaf or the standing, the Hajj is for the one he designated; otherwise, it is for himself.