Is it appropriate for a director of a parent corporation to serve as director of the subsidiary?

"'[I]t is entirely appropriate for directors of a parent corporation to serve as directors of its subsidiary, and that fact alone may not serve to expose the parent corporation to liability for its subsidiary's acts.' [Citations.] [] This recognition that the corporate personalities remain distinct has its corollary in the "well established principle [of corporate law] that directors and officers holding positions with a parent and its subsidiary can and do 'change hats' to represent the two corporations separately, despite their common ownership. [Citations.]" (United States v. Bestfoods, supra, 524 U.S. at p. 69.)