According to Ayatullah Sistani’s ruling, is it permissible for a man and woman to pray together without the required distance if one is performing obligatorily prayer and the other is performing a recommended prayer?
Man and woman should not pray together on the same line. She is not allowed to pray ahead of him even if she was a Mahram for him.
She should be during prayers behind him that her place of Sojood (prostration) should not be ahead of the place of his knees during his Sojood.
Wassalam.