What is the ruling on a daughter appointing her mother, sister, or brother to perform the marriage contract on her behalf, due to her inability to travel to the location of the contract, and would the contract be permissible in that case?

A woman is not permitted to marry herself or to marry off another woman. If the girl's mother or sister conducts the marriage contract, it is invalid.

As for her brother, he may marry her off if he is her guardian and qualified for guardianship (a Muslim, adult, sane male).

The marriage is valid if its conditions are met, such as the presence of a guardian and witnesses, and its rulings apply, even if it is for the purpose of obtaining a visa. It is not a condition for the validity of the marriage that the wife be present at the place of the contract.

A woman is not permitted to travel a long distance without a mahram or husband.