What is the ruling on refraining from visiting abusive relatives? Is greeting them in the street considered maintaining kinship ties? Is there a specific prayer for facilitating marriage, and what is the prescribed supplication for that?

A maternal uncle is a relative to whom ties of kinship must be maintained through customary practices in the country, such as visiting them on Eid. It is not permissible to sever ties with them, even if they mistreat you. Merely greeting them is not enough, for maternal uncles have three rights: the right of Islam, the right of kinship, and the right of neighborliness. It is permissible to supplicate for an easy marriage and righteous offspring, such as the supplication: "Our Lord, grant us from our wives and our offspring comfort for our eyes and make us leaders for the righteous." There is no specific prayer for facilitating marriage, but there is the Salat al-Hajah (Prayer of Need). Piety is the best means to fulfill needs and facilitate matters, as Allah Almighty said: "And whoever fears Allah - He will make for him a way out. And will provide for him from where he does not expect" and "And whoever fears Allah - He will make for him ease in his matter."