Duties of a wife towards her husband's family

No.

A relationship of marriage is a relationship of love, respect, courtesy, an easy going one with cheer and happiness. The husband does things though it is not his compulsory duty, like he will take her around on a holiday or for recreation, pay her medical bills or she will accompany him on haj and umrah trips. These are not his duties, but he does it in good spirit and to maintain a good relationship. Similarly the wife is expected to do things in the same spirit though it may not be an obligation.

And Allah Ta'ala (الله تعالى) knows best.