How can the wife's family be convinced of the permissibility of adopting the view of Sheikh al-Islam Ibn Taymiyyah regarding the issue of triple divorce pronounced in a single utterance and during a period of purity in which sexual intercourse occurred, knowing that they seek fatwas from scholars of the Maliki school of thought who consider this divorce to be valid?

There is no harm for one who acts upon the opinion of a trustworthy scholar, as long as he is content with his opinion and is not following his whims or seeking out dispensations. However, if a dispute arises concerning matters of divorce and the matter is referred to the Sharia judge, and he issues a ruling, then neither spouse is permitted to act contrary to his judgment; because the judge's ruling settles disputes in matters where there is a difference of opinion.