Is visiting relatives every two months sufficient, and are relatives only those mentioned [in the Quran/Sunnah], and does this visit fulfill the obligation?

The kinship ties that are obligatory to maintain are those between any two individuals for whom marriage would be unlawful if one were male and the other female. This includes fathers and mothers, grandfathers and grandmothers, brothers and sisters, children and their descendants, and paternal uncles and aunts, and maternal uncles and aunts. The obligatory maintenance of kinship ties is not restricted to a specific time. Its determination is left to custom, and it varies according to individuals, circumstances, times, and places. Whatever is customarily considered a connection is a connection, and whatever is customarily considered a severance is a severance.