Which is, thankfully, no longer necessary.
With the full release Steam version, multi-training now works like this:
1. Build the track with block brakes positioned as needed. For 2 trains, recommend 1 at the top of the lift device and 1 just before the return to the station. For 3 or more trains, add additional blocks behind the station. NOTE: AT THIS POINT, THE ADDITIONAL TRAINS WILL NOT BE VISIBLE.
2. Close the track-editing window at the bottom of the screen. Then make sure the ride itself is selected and its info window is in the upper right corner.
3. Go to the Operations tab of the ride's info window. You will see a box for number of trains. Under this is a checkbox for "Block Sections". Check that box, then increase the number of trains as desired. UNLESS YOU CHECK THE "Block Sections" BOX, EXTRA TRAINS WILL NOT APPEAR.
Once you complete Step #3, the extra train(s) will appear. at the block brakes behind the station and will be there for both testing and normal operation. And the number of trains is adjustable during play. If you built the ride with 3 trains but only have customers for 1 or 2, you can change that, which reduces operating costs and breakdown frequency.