Seamless knitting... not so seamless

Let's set the stage here: you've used the best yarn, best knitting structures, have the exact stretch and recovery attributes you want in your fabric but once you construct it, the garment doesn't stretch and the seams keep popping. This is what happens when you use a lock stitch on stretch fabric. Scott over at Cotton Inc. knit me down a stack of samples for some up coming trade shows utilizing the Hi-Grip COATYARN on a Santoni seamless knitting machine. The sports bra he knit down are double layered and needed to be tacked together to assist in the following construction processes. How did I get a stitch that stretches and recovers without breaking and popping? Was it a specific stitch type, thread, luck? Or is it the results of 15+ years modifying machines, knowledge of threads and yarns, and sweating it out through trial and error? If you want to set up a new cut and sew factory, need to know the proper stitch type to use, or need the equipment to do so, lets talk.