Is it permissible for me to visit my husband's sisters who do not observe hijab and intermingle with non-mahram men?

It is permissible for a woman to visit her husband's sisters or for them to visit her, unless shunning them would deter them from a sin, because such visits strengthen family ties.

For the visit to be permissible, the following Sharia-compliant conditions must be met: The husband's permission. Adherence to the prescribed Islamic dress code. The absence of non-mahram men during the visit.

If these conditions are not met, the visit is impermissible due to the potential for corruption, such as intermingling and unlawful gazing, as Allah Almighty says: "And tell the believing women to reduce [some] of their vision and guard their private parts and not expose their adornment except that which [necessarily] appears thereof" [An-Nur:31]. And as the Prophet, peace and blessings be upon him, said: "Beware of entering upon women," and "The in-law is death."