It's totally possible but you're wasting your time. The only close relative of cannabis is the hops plant (humulus). The government did experiments as early as the 1940's on this, trying to get rid of the "negative" effects of THC, but the experiment failed to produce anything of importance. More scientific experiments were conducted in the 1970's and they actually produced buds from the scion (tops and flowers) of a cannabis plant and rootstock of hops but the flowers contained no resin whatsoever. What is possible is to graft different strains onto one rootstock but in my personal opinion that's just novelty. Here is a pic of the successful, yet worthless hybrid:
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