Is the father's consent required for a marriage to be solemnized, and does his rejection of the groom nullify the girl's right to marry?

For a marriage to be valid, the presence of a guardian (wali) is a prerequisite. A woman does not have the right to marry herself or anyone else. The order of guardians is as follows: the father, then the paternal grandfather, then the son, then the full-brother (from both parents), then the half-brother (from the father's side), then the closest male agnate (asabah) in proximity. The guardian is obligated to marry his ward to a suitable (kufu') man whom she accepts. Otherwise, he would be deemed an 'adil (one who unjustly prevents marriage), and his guardianship would transfer to the next in line. However, if she requests to marry someone who is not suitable, he has the right to prevent her. If the guardian is not present, he may appoint one of his relatives to complete the marriage contract; otherwise, the guardianship transfers to the next in line.