Is it permissible for me to undertake the guardianship of a girl's marriage, in my capacity as the Imam of the Muslim community in the absence of the Sultan, and is the contract concluded between the girl's grandfather and the suitor valid?

For the validity of a marriage contract, it is a condition that the woman's guardian (wali) or his agent concludes it, based on the Prophet's (peace be upon him) saying: "There is no marriage except with a guardian," and his saying: "Any woman who marries without the permission of her guardian, her marriage is void." The woman's guardians, in order of precedence, are: her father, then his father (paternal grandfather), then her son, then his son, then her full brother, then her half-brother (from the father's side), then their sons, then the paternal uncles, then their sons, then the paternal uncles of the father, then the ruler (Sultan). If the guardians are unjust (preventing marriage without a valid reason), the guardianship transfers to the next in line until it reaches the Muslim judge. If there is no Muslim judge, a person of standing, such as the Imam of an Islamic center, can assume the role of concluding the contract. If she has a maternal grandfather or a maternal uncle, and they conclude her marriage contract in the absence of a Muslim judge, the contract is valid, and the grandfather has more right to conclude the contract than the mosque Imam. In summary: If the grandfather says to the suitor, "I give you in marriage so-and-so," and the suitor says, "I accept," the contract is valid.