Salam.

I know my husband has a responsibility to the women in his family. When I think of this I think his mother, aunts, sisters, and nieces. And I encourage him daily to reach out to everyone and help any one in need and all that... but does my husband have a responsibility to his brother’s wife? I can’t find anything online on this and personally don’t think he does. But in Islam does he? If someone has more knowledge on this or knows of a good resource please let me know. Thank you.