SWIM has more experience with D. stramonium. D. inoxia is about 1/2 as potent. With D. stramonium 3 seeds are usually enough for potentiation of most psychedelics, but it’s a stimulant. Sometimes 5 are needed. D. inoxia is a sedative. They are very different. The main alkaloid of D. stramonium is hyoscyamine, and the main alkaloid of D. inoxia is scopolamine.
I think 6-10 D. inoxia seeds would be a better dose for potentiation of other substances, since they are roughly 1/2 the potency of D. stramonium. But I don’t really know. That dosage range is completely safe and without negative effects on the mind. You’ll notice a slight sedative feeling and that’s about it. SWIM has only used D. inoxia about a dozen times, and he doesn’t smoke cannabis, so it’s really hard to say what amount is needed for cannabis potentiation. SWIM tried D. inoxia with mescaline, and with bufotenine, and it mostly introduced a lazy feel to the experience, and didn’t seem to potentiate them, but he only used 3 seeds, and I don’t think that’s enough. Others have used 10 seeds and felt potentiation of mescaline.
I think with only 10 seeds, it’s best to try all 10. If you used 6, that might be just enough and then the leftover 4 wouldn’t be enough to do anything.