The final series of the collection is Related Companies. The focus is primarily on companies that were originally founded by WPL but due to mergers or sales lost their direct affiliation with WPL’s companies. The exception is the final series, Lear Archives, which maintains a direct connection to WPL and his career. The Related Companies series has been divided by company, which are listed in chronological order of their existence and connection to Lear organizations: Lear Siegler, Inc., Gates Learjet Corporation, Canadair Limited, Static Power, Inc., and Lear Archives.

The first subseries Lear Siegler, Inc. (LSI) is a relatively small series that offers a glimpse into the early days of LSI, starting with its 1962 inception from a merger between Siegler Corporation and Lear, Inc. However, due to the paucity of materials, it is far from an in-depth reflection of the company.

The series is arranged into seven small subseries, administrative records, correspondence, financial records, photographs, publicity materials, research materials, and technical files. Materials are generally, but not always, arranged by date, with undated items at the end of each series. When able, circa dates have been provided.

Administrative records includes instructions for a new phone system, security-related correspondence, and an aerospace field survey report. Of note are booklets, reports, and two photographs related to LSI’s history.

Correspondence is comprised of a small amount of assorted correspondence. Of note is a September 21, 1965 letter to Ed Conklin from WPL. The letter is primarily personal in nature but does include a section on WPL’s thoughts regarding the 1962 Lear-Siegler, Inc. merger.

Financial records contains a 1964 announcement to shareholders about the annual meeting as well as a proxy ballot. Also included are drafts of the 1967 annual report and related correspondence.

Photographs includes 90 primarily black-and-white prints. Some are contact sheets of multiple images. The folders are arranged alphabetically by theme. Images feature aircraft-related scenes as well as various parts and products, including a crash survival memory unit, removable memory module, flight management computer and components, and a DTM interface panel. People are also depicted, including WPL, LSI President John G. Brooks, Albert Handschumacher, as well as unidentified people at the Aerospace Development Center dedication in December 1962.

Publicity materials includes assorted press releases and clippings, an agenda for an LSI-hosted “Low-cost navigation symposium,” and a 1964 commemorative booklet about PED-MARS (Power Equipment Division – Modernization Aero-Space Program). Also included is a 1964 letter to Sam Nash, president of Landsale Hampton Uniform Company, from LSI president John G. Brooks, refuting an alleged loss of contracts and including several undated (circa mid-1960s) press releases about LSI contracts. Attached is a brief note from Nash to Al Gorski, “This is the crap this man hands out.” Also included is one promotional 16mm film for the Siegler Corporation, circa 1960s.

Research materials consists of only two items: an April 1961 clipping of the Modern Machine Shop article "Let's discuss numerical control in simple language" and a 1968 booklet about NASA’s Michoud Assembly Facility.

Lastly, Technical files is also quite small and contains data sheets for various products, handbooks and instructions, and a LSI product and services directory. Also included is a booklet, “PAVE Phantom,” about LORAN-aided blind bombing weapon delivery system. On its front cover is a handwritten note to "destroy all but desired file copies.” The signature is illegible, but could be the initial “R.”

The Gates Learjet Corporation subseries provides a glimpse into the company activities from 1965-1994, after the merger between Gates Rubber Co. and Lear Jet Corporation when WPL had departed the company. Materials include photographs and textual materials, including clippings, press releases, correspondence, financial documents, and employee policy memos. Because it is a relatively small amount of material, the subseries has not been further subdivided; files are arranged chronologically.

Highlights include photographs, slides and photographic reproductions of concept art for various Learjet aircraft, including interior and cockpit images as well as in-flight shots. Featured aircraft primarily depicts the Learjet Model 31A, the Model 35, the Model 45, the Model 55, and the Learjet Model 60. There are also press releases for the Model 45 and Model 60.

Additional items of note include a 1969-1971 patent application for a polyphaser inverter with D.C. supply and a photocopy of a December 10, 1973 deposition of Charles C. Gates, President of Gates Rubber Co., regarding the April 1967 deal between Lear Jet Corporation and Gates Rubber Company.

Canadair is a quite small subseries consisting of materials collected by WPL and/or Lear employees as market research and to track company activity. The bulk of it is comprised of “media” about the company and its activities in the form of clippings, photocopies of clippings, and articles from 1977-1995. It also includes several reports related to the Lear-Canadair relationship as well as related reports regarding the Canadair Challenger CL-600, which originated as the LearStar 600. Additional materials include a Challenger timeline, technical data and diagrams, and an uncorrected galley of the book “Winging It” by Stuart Logie which discusses the making of the Challenger CL-600. Materials are arranged chronologically.

Also quite small, the Static Power Inc. (SPI) subseries focuses on its production of uninterruptible power supplies (UPS). Static Power was originally a division of Lear Jet Corporation but apparently branched out on its own at some point. The textual and visual materials are arranged chronologically.

The documents are mostly technical in nature and include manuals, proposals, a patent application for a “commutation circuit for power inverter,” and a presentation. There are a small amount of financial documents, including balance sheets, account charts, a sales incentive plan, and related correspondence. Of note are 197 photographs and one negative, in both black-and-white and color that depict power supplies and their parts and, to a far lesser extent, workspaces. Some images also include unidentified employees. Very few include captions, although most are numbered and include stamps, such as “Static Power Division” and “Lear Jet Photo.”

The final subseries provides insight into the Lear Archives. Though small, it ranges from the unofficial start of the Lear Archives, circa 1980s, to its more structured era in the 1990s to its termination prior to the donation of the collection to the Museum in 2000. It is arranged chronologically.

Materials focus on research and licensing requests as well as research undertaken by the archivists to track provenance of holdings and provide context, including inventories, correspondence, and interviews with former Lear employees. There are a small amount of administrative and financial documents, including possible exhibit display panels, background information on the collection and the archives itself as well as a 1999 invoice for Lear Archives website (www.lear-archives.com) design.

Of note is the 1998-1999 correspondence, including letters and fax transmissions, regarding the Lear Vapordyne Indy car. Initial requests by Ronald Shakespeare focused on possible sale or donation of the vehicle to the Lear Museum, which did not happen. Shakespeare also made requests for permission to license images of the vehicle for “research” in marketing efforts to sell the vehicle. Some correspondence discusses possible usage infringement by Shakespeare, although clear resolution of the situation is absent from the collection.