The phrase "auxiliary firms" is correct and usable in written English.
It can be used to refer to companies or organizations that provide support or supplementary services to a primary business or industry.
Example: "The success of the main project relied heavily on the expertise of several auxiliary firms that handled logistics and marketing."
Alternatives: "supporting companies" or "subsidiary businesses".
Abramoff was the apotheosis of the "K Street Project," a highly successful, years-long effort to turn the capital's "lobbying community" into a Republican auxiliary, by pressuring lobbying firms and trade associations to support a broad conservative agenda, hire only Republicans, and give money overwhelmingly to Republican politicians.
Charles Henry Cramp, the owner and son of the founder of William Cramp and Sons in Philadelphia, Pennsylvania, had a relationship with the Imperial Russian Navy dating back to the late 1870s when his firm built the auxiliary cruisers Afrika, Asia, Europa and Zabiiaka.
Firmer springs and dampers, auxiliary rebound springs, and a thicker rear anti-roll bar are the key to the transformation.
Furthermore, some results connecting the -monotonicity and corresponding resolvent operator are established, that generalize the results on the firm nonexpansiveness [2], while the auxiliary results on maximal -monotonicity and general maximal monotonicity are obtained.
Barker says the firm is benefiting from the increased demand for auxiliary power sources and would get a big cyclical boost from a strengthening economy.
Purchases by libraries have traditionally generated much of the revenue of local bookshops, but firms operating as specialist library suppliers are able to offer many auxiliary services, such as attaching plastic covers and inserting labels of ownership, because they deal in large-scale bulk supply and can afford to maintain machines for such processes.
Both the main station building and the auxiliary buildings were designed by Gudmund Hoel of NSB Arkitektkontor, the in-house architecture firm for the Norwegian State Railways, who were responsible for construction.
The Auxiliary to Bellevue Hospital Center.
Auxiliary power systems failed.
