My intention is to look after my wifes sister by making nikah to her as she is quite of a tender age and she is an orphan. Also to safeguard her from giong astray, not for any lustful or carnal desires and alhmd i am in a position wherein i can comfortably support both sisters. Jazakallah.
Almighty Allah Ta’ala enumerates all the women that are Haram (strictly
prohibited) upon an individual. One is joining two sisters in marriage.
If one marries his wife’s sister, the marriage will be invalid. It is
compulsory upon you to keep your distance from your wife’s sister. She has
to adhere to the laws of Hijaab in your presence. Rasulullah (Sallallaahu
Alayhi Wasallam) said, ‘The brother-in-law is death.’
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai