It is a very broad question. Synthetic cannabinoids of differing molecular structure will have different metabolic routes (how they are processed and broken down by the body to assist in easier excretion). Whether these routes overlap with the metabolism of Xanax is the question I would be asking. If a cannabinoid is metabolized by enzyme X, and the xanax is already being metabolized by the same enzyme, then the effects of both will be heightened as they are now both being eliminated at a reduced rate by enzyme X.
A subjective report, I have combined with 122, 210, 250 and did not notice extended duration of effects or anything like that, but I would proceed with extreme caution and small doses until you become attenuated to how your body reacts to the compounds.