SPARTANBURG, S.C. — In a move that will Bolster J.M. Smith’s offerings in the Northeast, Burlington Drug Co. and some retail operations assets of Pharmacy Health Services will be joining J.M. Smith under a merger agreement, the companies announced Tuesday. Under the agreement, Burlington Drug and PHS ill operate as subsidiaries of J.M. Smith, with Burlington Drug continuing to manage all operations, customer service and sales functions out of its Milton, Vt. Headquarters. PHS will continue serving customers at their existing locations.