What is the Sharia ruling regarding a husband's refusal to accompany his wife to witness the Udhiyah (sacrifice) taking place at the home of his first wife, in order to avoid upsetting the first wife and children, thereby depriving the second wife of participating in this joy?

The justice required between wives is justice in nocturnal lodging and in financial support. Justice is not required in the distribution of the sacrificial animal (Udhiyah), but striving for fairness in every apparent matter is better to avoid discord. The Salaf (pious predecessors) even recommended justice in everything, including kisses, perfumes, and ablution. It is possible to reach an understanding with the husband for him to alternate between the two wives in the distribution of the sacrificial animal, and for the husband to be with the wife whose turn it is on the day of Eid, unless the other wife consents otherwise.