I also find this thread completely fascinating, and most informative and enlightening. Some of this is still unfamiliar to me though, like 'v' or 'vee'...what is that exactly?
As for the new third having a previous relationship or current relationship, well we aren't really at that particular point but if the person we fall in love with is involved elsewhere, then we would definitely have to reevaluate and since that person would be part of the new person we want to be part of then we together would have to discuss if we would want to continue or if it would be better to let them go. I don't want to sound selfish, but we know what we want, and we hope to find a single person to add to our marriage, not a couple. We kind of don't think that will be much of an issue simply because we won't be looking for that couple, but be seeking out a single who hopefully will be seeking for a couple like us.
You may start thinking now that what if the new person meets someone and wants the chance to explore their feelings with that 4th person...that would not be something we would be willing to be a part of. We aren't looking for another couple, we aren't looking for a quad relationship, or communal marriage. We simply want one more person to be married to. And if that person is married to us, then there would be no others but us. We want a wife, or a husband, a faithful spouse for the rest of our lives.
Now the question has been raised about the possibility of the new person dieing before me or D. I hadn't really thought of that but we discussed it and we both agree that if that should happen, then we will have been blessed with the opportunity to have had a loving, nourishing relationship with that soul and would be able to comfort each other during our time of loss. Would we then go seek out another? Maybe, maybe not. To find it once is apparently a long shot, twice might be impossible.
I really appreciate the responses from each and every one of you. This is keeping the conversations between me and D very interesting indeed.