Is it valid for a person to fast on behalf of two individuals (the fasting person and their ill one) for 24 hours without a pre-dawn meal (suhoor)?

A sick person who is unable to fast, either their illness is temporary and they must make up the days after recovery, or it is chronic and they must feed a poor person for each day. Fasting is only during the day, from dawn until sunset. Nighttime is not for fasting, and it is not permissible to make the nights of Ramadan a time for fasting. Indeed, the Prophet, peace and blessings be upon him, forbade continuous fasting (without breaking it). It is not permissible for anyone to fast on behalf of a sick person, as the fundamental principle for physical acts of worship is that a Muslim performs them himself, and representation is not allowed in them.