What must a couple do to return to each other after a revocable divorce that occurred four years ago, especially given a previous fatwa that stipulated the divorced woman must marry another man to be returned to her first husband?

If a man divorces his wife once and her 'iddah (waiting period) expires, she becomes irrevocably separated from him with a minor separation (baynunah sughra). To take her back, he needs a new contract with all its pillars (wali, two witnesses, mahr). As for a woman divorced thrice, she does not become lawful for her first husband until she marries another man, he consummates the marriage with her, then he separates from her, and her 'iddah from him ends, based on the Almighty’s saying: {Divorce is twice} and {And if he has divorced her [for the third time], then she is not lawful to him afterward until she marries another husband}.