Is it permissible for the wife's brother or any of her family members to issue a ruling (fatwa) that encourages the wife to disobey her husband's commands, in matters that do not involve disobedience to Allah, and to change her agreement to these commands, and what is the punishment for this if it is not permissible, supported by evidence from the Holy Quran and the noble Hadith?

It is not permissible for the wife's family to incite her to disobey and defy her husband, even if what they are calling her to is not forbidden. This is due to the Quran's prohibition of causing corruption and the Prophet's (peace be upon him) saying: "He is not one of us who incites a woman against her husband." Whoever strives to corrupt her should be advised, and if they do not desist, they should be reprimanded by referring their matter to the judiciary.