If there was a thing that was very important to me and where I'm trying to go in life, and then someone told me they could get it for me or take me there, and then that destination started coming into view for me, and then the person said "Hey, would you like to go somewhere else and totally forget all about that place?" I would be pretty angry about that.
It sounds like the three of you have three different views on where to go and how to get there. So different, in fact, that you need to do a lot more communicating and compromising. Communicating and compromising can be very enjoyable. Even when someone has to sacrifice something for the benefit of someone else.
I hope you all get to talk it out some more. I hope you all assume good intentions. I get the sense that HMA is coming from a very genuine and well meaning place in an attempt to help everyone have what they need to thrive. We don't really have a legal system that tries to facilitate that in any way where polyamory and marriage are concerned. But polyamorous couples have figured it out in the past. And you all seem pretty smart and determined.
Still rooting for you all.