Can someone please enlighten me on what the relationship was between the UP, MILW & MP? I've seen some photo's on Railpictures.net, showing Loco's painted in the same livery as the UP, but with "Missouri Pacific" on the side. Also seen some shots of MILW passenger equipment in the UP livery too. Were mergers proposed between these Railroads, or was it a case of there being shortages of passenger equipment on UP Dome-liners/ Stream-liners, which these other two RR agreed to provide stock to avoid the short-falls?