In Taca Intl. Airlines, S.A. v. Rolls-Royce of England, 15 NY2d 97, 102, 204 NE2d 329, 256 NYS2d 129 (1965) the Court of Appeals asked "was the subsidiary a really independent entity or a mere department of the parent? If the latter, then obviously the parent was doing extensive business in our State through its local department separately incorporated as the subsidiary."
The Court in that case found that the domestic subsidiary was a mere department of the foreign parent because of the parent-subsidiary relationship, the sharing of executive personnel between the two, similar training and policies between the two entities and the financial dependence of the subsidiary on the parent.
Upon these factors, the court reasoned that service on the subsidiary constituted service on the parent. (Id.)