Splitter Required, Single Controller Works Fine
I have a jacket and pants as well, and had the exact same problem. Talked to Gerbing, and they recommended a splitter, as described here:
When wearing a vest, which has no glove plugs, and also wearing gloves and insoles (or pants), the splitter connects the gloves and insoles (or pants).
The link above will get you to the page on the Gerbing site.