Is the wife's brother considered one of her immediate family members according to the rulings?

The jurists have adopted the permissibility of arbitration between spouses when their dispute intensifies, based on the Almighty's saying: ﴿And if you fear dissension between the two, send an arbitrator from his people and an arbitrator from her people. If they both desire reconciliation, Allah will cause agreement between them. Indeed, Allah is ever Knowing and Acquainted [with all things]﴾ (An-Nisa: 35). It is preferable for the two arbitrators to be from the relatives of the spouses because they are more knowledgeable about their inner circumstances and more keen on reconciliation. This includes the wife's brother and the husband's brother, provided that they are just, rational, and righteous.