I "created" an Illinois Central Fast Mail consist which transported mail from Chicago to St. Louis. The IC smooth side baggage/RPOs, IC Harriman RPO, IC mail baggage Express box cars, UP Express and Merchandise cars have been collected over a period of three or so years. The head end cars are MTH Premier and all the box cars are Weaver. I added the UP box cars to the IC consist as so far I been able to locate only five Weaver IC mail/baggage box cars. But for my tastes, the added colors of the UP box cars actually makes for a more interesting train.
I decided that justification for the UP cars in the IC mail consist lay with the fact that I have put together the UP City of St. Louis (Wabash/UP combined passenger service from St. Louis to LA and San Francisco) and the UP cars could be included, probably not too realistically, in one of the passenger train runs in which Wabash diesel units pull a UP passenger car consist from St. Louis to Kansas City.
Hope this helps.
