The term LASHUP is NOT, was NOT first used by Lionel. Not sure where or why this non-sense keeps coming up.
Charlie
Jerry Pinkepank, who is a highly-regarded railroader - authority on diesel locomotive model designation and former official at BN, presently a professional railroad consultant, among other professional positions - wrote an article which was published in Trains, years ago. The title was Lash 'Em Up and the subject was an explanation of how locomotives are connected and how they operate in multiple unit consists. There was some information about jumper cables and receptacles, air brake operation, etc. Actually, it was a good article, and, even today, about 30 or 40 years later, it would still impart useful information to curious railfans. Because Trains is the most widely read railfan magazine, the term may have grown from that use of it in print.
He heard a Foreman utter the title of his article at some roundhouse somewhere. So, it really did get used somewhere on some railroad, but it is neither the common nor correct term for a locomotive consist. I never heard anyone say "lashup" in my 37 years of engine service and service as a Company officer n the Operating Department who worked closely with the Mechanical Department. Nor did Jerry Pinkepank, either, I'll bet. But he needed a catchy title for his article about m-u operation.
Let's not say "lashup", except when discussing TMCC or Legacy control system questions or issues.