While i seem to recall someone on here saying that it's "impossible", most people are simply saying "if you want this to work, you need to go about it differently."
It seems as though recently, i must be going crazy, because people have been responding to things others have not said, as if these things WERE said. It may not be "impossible" to have a "successful" (whatever that means to you) triad, but it IS impossible to have a productive discussion about a topic with a person or persons who respond to things you didn't say as if you said them. I have a friend that sometimes does this. I'll say something, and he'll answer with sentences that are constructed in such a way that i can tell he made assumptions and extrapolated incorrectly from them. When i ask him how the hell is that an answer to what i said, he goes "ar, um, well you said abc and xyz so i assumed the rest of the alphabet was included".
And that, my dear poly people, is the problem with most people, poly or not, and it is also what is at the root of most of the relationship problems on here. There cannot be useful or beneficial exchange of ideas if people insist that others said shit they never said.
As for myself, i've decided that after one or two attempts to point things out, and an individual continues to be obtuse, then that individual gets filed under "nothing to say worth hearing" and i don't waste my time on them.
I know it's hard to believe, but there are others like me, and we know who we are.