Is it necessary to back out of a marriage due to disputes between the father and the bride's maternal uncle over agricultural land? And would completing the marriage be considered an act of disobedience to the father, or would abandoning it be an injustice to the girl?

If a father refuses his son's marriage to a girl due to a dispute between him and the girl's maternal uncle, the son is not obliged to obey his father in leaving her, and he is not considered disobedient to him. The son can try to persuade his father to marry her. If the son wishes to forgo the marriage out of obedience to his father, there is no sin upon him in that, and an engagement is a promise to marry that can be broken for a valid reason. He must always honor his father and obey him in what is right.