Which father is attributed paternity when two men have sexual intercourse with a woman during the same purity period?

Primary text

When two men have intercourse with a woman during one period of purity, and the resulting child could potentially be attributed to either father, paternity is established through expert physiognomists (Qafah). Paternity is established with whichever of the two men the physiognomists attribute the child to. This scenario arises if they share ownership of a slave woman they both approach during her purity period, or if a man approaches another man's wife or slave girl under a mistaken belief (shubha), such as finding her on his bed and mistaking her for his own wife or slave, or calling for his wife in darkness and another man's wife or slave responds. It also applies if both marriages are invalid (fasid), or if one marriage is valid and the other is invalid, such as one man divorcing his wife and another marrying her during her waiting period (Iddah) and having intercourse with her, or if a slave girl is sold and the buyer has intercourse with her before seeking purification (istibra').