Is it permissible for a girl to marry a man, already married, with whom she had previously committed adultery and repented, and whom she still desires greatly, despite her father's refusal and her wish not to wrong his wife and daughter?

The father should be persuaded to agree to the marriage. If he insists on refusing without a valid reason, then obedience to him is not obligatory, and the matter can be referred to the Sharia judge to arrange her marriage. Repentance from indecency is obligatory, and one should conceal their sin, while being careful not to fall into it again in the future. There is no objection to the marriage of repentant individuals, and there is no injustice in a woman being a second wife. As for a woman's work, it is subject to Sharia guidelines.