What is the ruling on attending gatherings of backbiting that occur among grandparents and aunts, if these gatherings are almost daily and difficult to avoid, and am I sinful for that? And how can one reconcile honoring grandparents and aunts with avoiding these harmful gatherings?

Guidance is in the hand of Allah, and your advising your family is what Allah has made incumbent upon you. Their misguidance will not harm you if you are guided, for Allah, the Almighty, says: "O you who have believed, upon you is [responsibility for] yourselves. Those who have erred will not harm you when you have been guided." If they engage in forbidden acts, then leave their company. Obedience to parents takes precedence over obedience to grandparents when there is a conflict, and there is no obedience to anyone in disobedience to Allah, for the Prophet, peace and blessings be upon him, said: "There is no obedience to a creature in disobedience to the Creator." Allah does not burden a soul beyond its capacity, so be patient and seek your reward from Him.