ancillary
an-cil-la-ry
noun
A supplementary item, service, or person supporting a main one.
"The company sells many ancillaries alongside its main product."
adjective
Providing necessary support to a primary activity or operation.
"Ancillary staff provide essential support to the main team."
Thesaurus
Synonyms: appurtenant, adjunct, accessory, adjuvant, supportive, auxiliary