OK, let me see if I can contribute to this. It may be a bit lengthy so grab a coffee or adult beverage and let's sort it out.
First off, it will be necessary to clarify what you mean by "Ontario Midland roster". Are you listing locomotives OWNED by OMID, or those LETTERED for OMID, or those which OPERATED on OMID? It sounds like being picky, but that distinction can affect greatly what we come up with. Also, the sequence on the following acquisitions may be off, they may have bought X BEFORE Y despite my saying the opposite.
Shortline railroads are quite often short on cash, especially at start-up. And with a new company which may or may not survive, people can be reluctant to invest their money. So as OMID was created, a separate company was formed, RSA Leasing. The plan was for RSAL to purchase locomotives and other equipment and lease it to OMID and ONCT (and others as well) at below the typical rates. This helped the new companies get better power than their finances would have allowed, yet protected the investors - if OMID had gone belly-up, the locos could have been sold off to recoup the investment. RSAL was a separate corporate entity, some OMID shareholders also invested in RSAL, some did not. Likewise some RSAL investors did, and some did not invest in OMID (and ONCT).
As the companies were planned, RSAL bought 3 locos from N&W - 361 and 408 were sent to OMID, 2865 went to ONCT. For simplicity, they were shortened to 36, 40 and 86. And here's where that thing about how you define the roster comes into play. A year or two after startup, 86 needed some TLC which needed to be done in the Sodus shop. The 40 went to Victor, the 86 went to OMID. And while 40 WAS lettered for ONCT, the 86 was never relettered OMID. Regardless, 86 stayed on OMID for quite some time, and was used in regular service there. There are pics of 86 switching at Marion NY, before that branch was abandoned. Eventually 86 went back to Victor and 40 returned to OMID and was re-stencilled for OMID.
Regarding #14, it was never owned by, nor used on, Ontario Midland. When Conrail was formed, it went from BCK 46 to CR 9662, before being purchased by RSAL and sent to Victor. It was used in service on ONCT, and in fact it was pictured in a newspaper article about the first car being delivered to Dekalb Agresearch, just west of the Rt 332 overpass. It was still in its BCK Bicentennial paint. For a time RSAL had renumbered it back to 46. It was leased - NOT sold - to NY&LE for a time, then returned.
At a date I can't say from memory, the two Wyandotte Terminal switchers were purchased by RSAL and sent to Sodus. #17, the former NKP 79, was turned out fairly soon and sent to Allegheny Southern Railway. The former B&O engine became OMID 16, and did operate on OMID, lettered for OMID, but owned by RSAL (and still in orange, not black).
With the two switchers being 16 and 17, the former BCK 46 was renumbered to 14. Why it was not designated 15 I don't know. The unit was cleaned, prepped and painted at Victor. As lettering was being done by ONCT guys on their own time, a rush demand for its use at North American Car Co's Sayre shop sent it away with only one side bearing the "Ontario Lines" lettering.
Ontario Lines started with OMID and ONCT. The Ontario Eastern was added, and both Allegheny Southern and Jersey Southern were subsidiaries of ONER. Eventually those 3 ceased operations and only the original 2 lines remained. Eventually it was decided that the two railroads would acquire the 3 original locos respectively, and RSA Leasing was dissolved. Only at that point did OMID actually own the engines.
And if you want to define "roster" as locos that pulled trains on OMID, there are at least 3 more. Golden Spike Railroad Services had some GP9's off lease which were sent to OMID. Both GSRX 5913 and 6145 were used on OMID freights in testing after work. They were not owned, leased nor lettered for OMID but DID perform work on the line, in fact the last train to ever leave Red Creek NY was pulled by GSRX 5913 (before its repaint out of C&O colors) And Golden Spike also owned coaches, and operated many excursions over OMID using the Geeps over the course of at least 2 years. And separately, a different OMID employee, George Hockaday, lovingly repainted a CN FPA4 into D&H colors. This, too, was used on various freight and passenger runs, altho a very brief time. The change in management, coupled with the split of the OMID and ONCT, ended the operation of these colorful additions to the OMID's history.
Hopefully this has not put too may to sleep, but keeping facts straight and history accurate requires getting the details as precise as possible.
