I know exactly what you are talking about (grafting, that is). I did a lot of reading on that. I've heard varying reports saying that it works or doesn't work. Apparently,hops will have no problem grafting onto its close cousin, but it is still a hops plant (with no assimilated attributes from the relative plant).
The only benefits that I can see from this is that hops have a weak root system compared to the cousin plant, so if you graft a hop bine onto the root system of the other plant you should have higher first year yields, earlier in the season. Unfortunately, the two separate plants keep their respective DNA structures and function in a symbiotic relationship--the bines collecting the sun's rays and the roots collecting water and other nutrients.
Farmers do this all the time with apple trees because it is faster than starting from seed.
The only way I think you can achieve the affect you are looking for is through cross-pollination. That is the only way to really change the DNA. Unfortunately, most hop plants (as well as the cousin) are sterile clones that do not produce seeds. Even if you were able to find both species of fertile plants, they are still two different species and there is no guarantee that cross-pollination would work. If it did, you might spend years getting the results you want. Do a little research on Mendelian genetics.