Is it Halal (lawful) or Haram (prohibited) for a woman to kiss her sister's husband
or for a man to kiss his sisters-in-law and for Muslim women in general to exchange kisses with their brothers-in-law?
This is not permissible according to the general evidence that declares this to be Haram from the Qur’an and Sunnah (whatever is reported from the Prophet). (Part No. 17; Page No. 420) Some people have become accustomed to this practice, but it is a violation of the Shari‘ah (Islamic law). May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.