There is no evidence what so ever that the Prophet himself allowed such marriage. Both of the ladies were divorcees of two sons of Abu Lahab, the enemy-uncle of the Prophet (SAWA). After their divorce, they were free to marry whom so ever they wanted from Muslims. In fact, the real daughter of the Prophet Muhammad (SAWA) was Fatima (AS) and he marriage was by order of Allah (SWT). It is mentioned in Sunni books that when Ruqayyah passed away, the Prophet (SAWA) did not allow Othman to attend her funeral.