29 CFR § 779.210 - Other activities which may be part of the enterprise.
(a) An enterprise may perform certain activities that appear entirely foreign to its principal business but which may be a part of the enterprise because of the manner in which they are performed. In some cases these activities may be a very minor and incidental part of its business operations. For example a retail store may accept payments of utility bills, provide a notarial service, sell stamps, bus and theater tickets, or travellers' checks, etc. These and other activities may be entirely different from the enterprise's principal business but they may be performed on the same premises and by the same employees or otherwise under such circumstances as to be a part of the enterprise.
(b) Sometimes such activities are performed as an adjunct to the principal business to create good will or to attract customers. In other cases, the businessman may engage in them primarily for the additional revenue. Some such foreign activities may be conducted in a more elaborate manner, as where the enterprise operates a bus stop or a post office substation as an adjunct to a principal business such as a hotel or a retail store. Where in such a case the activities are performed in a physically separate “establishment” (see §§ 779.303–779.308) from the other business activities of the enterprise and are functionally operated as a separate business, separately controlled, with separate employees, separate records, and a distinct business objective of its own, they may constitute a separate enterprise. Where, however, such activities are intermingled with the other activities of the enterprise and have a reasonable connection to the same business purpose they will be a part of the enterprise.