Comments
Agree, this should be an option in standard. We have customized to solve this many times and also agree that status loaded should give option to post and print packing slip. We have used Print Management to set up printer that has worked well for us as this gives many options to set up where to print.
Visualization didn't work as I designed it and I can't edit, so here's another attempt:
.................................................................sequence start
.................................................thread 1............................thread 2
.....................................................|.......................thread 3.............thread 4
.................................................step 1..........................|........................|
.....................................................|...............................|........................|
.................................................step 2 <<<.---------------|--------------------|