Just to nitpick, you probably meant predecessor railroads, not parent railroads. BN wasn't a subsidiary of another railroad, it was the result of a 1970 merger between several railroads that created a new railroad, Burlington Northern.
I had thought about the archives site after I posted the request and I had forgetten about the BN power site (I even had that in my bookmarks. :( Too many bookmarks, not enough use.) But it did answer my question. I can go either way. Thank you for the assistance and the reminder on the sites.
...and a bit more....
http://www.rrpicturearchives.net/locolist.aspx?id=BN
"One difference between pessimists and optimists is that while pessimists are more often right, optimists have far more fun."
This should be a good start: http://archive.trainpix.com/BN/ROSTER.HTM
Got yet another question for my forum friends: Does anyone know what the production eras were on the SW1s that BN obtained from its parent roads? I have a prior run Walthers SW1 for my freelanced layout that serves a car ferry terminal & yard. The engine is a former BN unit. According to the instructions, SW1s were produced both before WWII and after. The ones after the war had the smooth transition while the ones before didn't.
Thank you for any help the forums can provide.