biadjoint biequivalence

Dear Categorists - I know someone who needs to construct a "biadjoint biequivalence" between bicategories, and is not relishing the task. If somebody was trying to construct an adjoint equivalence between categories, and was not relishing the task, I might suggest that they construct an equivalence, and then use the theorem that any equivalence can be improved to an adjoint equivalence. Has someone proved that any biequivalence between bicategories can be improved to a biadjoint biequivalence? Best, jb