1) Accessory 2) Adjunct 3) Adjuvant 4) Appurtenant 5) Auxiliary 6) Furnishing added support 7) Of lesser importance 8) Subordinate 9) Subsidiary 10) Supporting 11) Supportive 
An ancillary provides necessary support to the operation of an organization. Other uses of the word include: ...
auxiliary; secondary
• (a.) Subservient or subordinate, like a handmaid; auxiliary.
Subordinate or auxiliary to something or someone else; supplementary.
An'cil·la·ry adjective [ Latin ancillaris , from ancilla a female servant.] Subservient or subordinate, like a handmaid; auxiliary. « The Convocation of York seems to have been always considered as inferior, and even ancillary , to the greater province. Hallam. �...
Type: Term Pronunciation: an′si-lār-ē Definitions: 1. Auxiliary, accessory, or secondary.