This rose is still under patent, and that covers the whole rose. Copyright is something different. The name Dark Desire is also probably trademarked. I don't know if this rose would make a good rootstock, but if it's still under patent, you'll have to wait, I think. Diane

The stocks in use in various areas are sometimes those which have proven themselves the easiest to root and the easiest to bud to in those areas. Prior to Dr, Huey being "the" stock in California production, Ragged Robin, Gloire des Rosomanes was the stock of choice there. It's thought some time around WWII, while collecting cuttings for the next year's production, cuttings of Huey were collected, rooted and budded to. Once it was discovered how much better those plants performed, the choice was made to switch to Huey for production. Sometimes, it's scientific study, sometimes it's serendipity.

Yes, patents mean you aren't supposed to propagate the patented rose. If you decide you wish to attempt rooting it and testing it as a stock for your garden, that choice is yours to make and I am not going to judge either way. You will need to successfully root lengths of it. You will need to remove all but the top one or two buds from each cutting so no growth of new shoots comes from anywhere but the top growth buds, or those new shoots will be "suckers" you will have to deal with on your newly budded plants. Once they are rooted, you can decide whether you wish to "T" bud, chip bud, cleft graft or how else you wish to bud to them. Personally, I prefer chip budding as it is far less dependent upon the bark of the stock being able to be lifted easily, so budding can be successfully accomplished over a much longer period than it otherwise might be able to. There are many videos on line about how to accomplish each method of budding (or grafting, it's pretty much the same thing, except you bud or graft single buds, but you can also graft stems to stocks).If you wish photos of chip budding, I have some on my blog.

The hardest part of what you propose is rooting the stocks. Practice it until you're proficient then have a ball budding! Good luck!