subsidiary

Auxiliary or supplemental.

chief ruler and principal head everywhere, not suffragant and subsidiary

They constituted a useful subsidiary testimony of another state of existence.

Secondary or subordinate.

a subsidiary stream

By one o'clock the place was choc-a-bloc. […] The restaurant was packed, and the promenade between the two main courts and the subsidiary courts was thronged with healthy-looking youngish people, drawn to the Mecca of tennis from all parts of the country.

Of or relating to a subsidy.

subsidiary payments to an ally

George the Second relied on his subsidiary treaties.

A company owned by a parent company or a holding company, also called daughter company or sister company.

A subordinate theme.

One who aids or supplies; an assistant.