I have not created an additional step.
I think you miss the real point of the problem.
The client letter always prints first, it is not part of the Print Order selection. If you do not choose the client letter then the first item on the Print order list prints first, if you choose to include the Client letter then that prints first and NOTHING can print in front of it.
I setup the order I want things to print, then print once. I am not printing twice, and I am not moving around paper even when I print to paper, and I am not ever going to waste time taking the pdf elsewhere and waste time moving things around.
Adding the slip sheet to the client letter is reducing our options by including it in the Client letter block.
Computers should be automatically taking care of the stupid stuff and let me focus on CPA stuff, not filing and paper shuffling.