Lawyers are preparing for battle in Essex County, N.J., over whether the $10 billion estate of Taiwanese industrialist Wang Yung-Ching, who died intestate last year in his Short Hills home, should be administered in New Jersey, in whole or in part, and which law should apply.

The case involves not only extensive financial and commercial holdings but also an extended-family relationship that includes a widow, two putative secondary wives — who under Taiwanese law would share in the estate — and nine children, all of whom have lawyered up.