Deputizing others to throw the pebbles

Q 2: My mother performed Hajj twice, but she did not throw the pebbles (at the stone pillars during Hajj) by herself in both times; it was my father who did so on her behalf. During the first she performed Hajj, she was physically fit to throw the pebbles by herself, but she had a baby with her. In the second Hajj, she was quite old and unable to throw them. That is why my father once again threw the pebbles on her behalf. Are her two occasions of Hajj valid in this case or not?

A 2: If your mother requested your father to throw the pebbles on her behalf during the two times she performed Hajj, for the reasons mentioned in the question, then we hope that there is nothing wrong with her doing so.May Allah grant us success. May Peace and Blessings of Allah be upon our Prophet Muhammad, his family and his Companions!