th9x

I have the Iris+ with the FS TH9X Transmitter. The transmitter came with the Iris+ installed on it. Can I add another model to this transmitter? How or what do I need to do to do this? I did read about a Smartie Parts card (SP Basic (9X Programmer) [SPBASIC] - $18.90 : SmartieParts.com) to add...