What is the ruling on a wife praying beside her husband or behind him in the same room if he is performing a supererogatory prayer and she is performing an obligatory prayer?

If a husband and wife pray individually, the wife may stand wherever she wishes next to her husband, or in front of him, or behind him, because there is no connection between their prayers. However, if the wife is led in prayer by her husband (i.e., she is his congregant), then she prays behind him. If a woman prays alongside a man in congregation, her prayer is valid according to the majority of scholars. The prayer of the man is not invalidated by the woman praying alongside him, according to the majority.