Marcus, you are correct, there are some unresolved issues and I am not sure how to "fix" the problem. Or even if it is my problem to fix. I am very attached to B...... we have been together for 10 years (mostly in a LDR) and marrying him is something I really want to do. Now that I am retired we can be together all the time. I currently live in the US for 6 months and in Canada for six months. Getting my visa will solve that issue and I can be in the US all the time.This whole situation sounds like a bit of a powder keg. Are you concerned about the longevity of your association with these people?
Having a third of my polycule experiencing what I would classify as some pretty intense feelings of jealousy and fear would be a big red flag to me. It sounds like you guys are already all living together which puts you elbows deep into this thing already, and getting married would seem to get you even more encumbered.
If it really is just a residency issue, maybe you guys can figure out a way to get you into a guest room so they can have their marriage and you can continue to live your life. You guys can get married via a non-ceremony path for the residency issue, and Kay can claim B publicly (which seems important to her).
Living with another partner was never on the table until a year ago and it has taken some getting used to. I wasn't really consulted as Kay moving in happened before B asked me to marry him. And to be honest, it was a manner of some urgency as Kay was living in a trailer with poor heating and had a raging case of pneumonia. She moved over to B's house and took two months to get better. And then the NRE was so sparkly that he just asked her to stay.
I am willing to do whatever work is necessary as I truly don't want to give up a love that is so special to me.