Problems between sister-in-laws are common. This stems from that each one wants to better and compete with each other. Instead of focusing in getting your right, we suggest you forgo your right, helping you in getting more respect and saving you from more problems.
We suggest the sister should not get involved in the brother’s private life. This will only create unnecessary problems and rift in the family.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai