Is the second wife sinning if she cuts off communication with her husband's family, who do not reciprocate her attention or visit her, despite her continuous attempts to get closer to them?

The husband's family has no special right over the wife if they are not her relatives. There is no sin upon her for not visiting them or contacting them, as long as she avoids the forbidden abandonment that exceeds three days, which is achieved merely by greeting or returning a greeting. It is better, if no harm results from it, for her to maintain ties with them and be kind to them, overlooking their shortcomings. This is from the ethics of noble people, and a kindness to the husband, and good companionship.