What happens if the above married girl gets child and emrace Islam. Now what should she do. What happens if the girl marries her own brother in the above case as practiced in some tribes?
If the girl embraces Islam, then the husband and wife will have to be
separated and the child will remain with the mother as a Muslim. If the girl
marries her brother then too, the two will be separated and the Nikah will
be broken. (Fathul Qadir vol.3 pg.415, Darul Fikr and Shami vol. 3 pg. 189,
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai