Roger,
In response to your earlier message, I tried again to build a lashup using the two paired engines (that have identical ID's) with the Bistro car but was unsuccessful due to "duplicate engine" errors.
If you happen to have any Lionel soundcar (effectively the Bistro Car functionality), see if you can come up with a successful lashing to the engine pair using the Build button. If you are successful, we'll document the procedure in the paper.
For now, I think the approach described in the starting message is the easiest way to effectively do the lashup without using the Build command.
