Is preventing his sister's children from seeing them after a dispute with him considered a severing of kinship ties that warrants God's wrath, and could the situation have been handled differently to avoid this outcome?

We pray for mercy for your sister and guidance for her husband, and we thank you for your commitment to maintaining kinship ties, as it is a great reward.

We pray that the father of the children does not deprive you of communicating with them unless there is a legitimate reason. You can continue to advise him and involve influential people in the community.

If he insists on his stance and communication by phone or general meetings is possible, there is no sin. If it is not possible, then you are not sinful.