Hmm, I don't know. I always feel very sorry for K when you post about her. I find your view of her very harsh.
I think it's a very big deal for a poly person to marry one partner and not the other, when both partners are nesting partners and life partners to the hinge. Especially when the non-married partner is clearly not okay with it. Unless there is a very clear financial/legal/medical reason to marry one partner and not other, it seems like a recipe for misery all around.
I guess your relationship with B and your plans to get married to each other predated his relationship with K; but in that case, I wonder if B was clear about setting expectations with K regarding what life partnership with him would look like.
It sounds like B tells K that she is just as important as you in love, status, security, family, etc. But K can sense that's not really true.
So she's tried coming up with a bunch of different compromises that would demonstrate the same things that marriage does (since marrying two people is not legal). Handfasting, for example, and now legal adoption.
The handfasting ceremony was a good compromise (and pretty typical for many poly people). I can understand why you didn't want it on the same day as your wedding, but I can understand why K initially suggested it...it would have been a clear demonstration of B's equal commitment to his two life partners, regardless of which one was his legal wife. Standing up in front of all one's friends and families for a wedding conveys a lot of status and support on the couple getting married.
It seems sort of sad to me that K and B's handfasting ceremony was clearly a concession to her and maybe not even something that B really wanted, or was as excited about as he was for his wedding to you. And if that's the case, can you really blame her for feeling insecure? Wouldn't you also feel something was missing in your life and your heart if you were in her place?
Maybe I'm wrong and B truly, deeply loves K, and his relationship with her is healthy and delightful. It's hard to tell because your posts about K are so condescending. Look at the language you use:
1. enormous hole in her psyche
2. she wants to make sure she is in line for an inheritance someday
3. B has assured her that she will be looked after
4. She still feels like she doesn't belong
5. She thinks that being "adopted" will make it better....Has anyone else here dealt with "adopting" a partner?
6. I think it is rather cringe worthy
7. I would not put my name on any such document
8. We will keep hoping that she will start to feel more secure soon
See my notes below on your comments above (numbered).
1. We all know people who seem to have something missing internally and are just deeply unhappy with themselves and often spend their lives in bad relationship after bad relationship because they can't fix what's broken inside them. But... is this how you view your metamour, the person your life partner picked to be his other life partner? Perhaps the hole in her psyche is the pain of being in a polycule where she doesn't feel equally loved, while having a metamour who views her as one big walking psychological problem?
2. She's not some third cousin clamoring for an inheritance. She wants to make sure she is financially secure in old age if her life partner dies, whereas you won't have to jump through hoops to inherit B's assets, since he's your legal spouse. I think you said she struggles more financially than both you and B. If so, it seems like she has a reasonable concern.
3. That she'll be "looked after" sounds paternalistic, like she is a great-niece or housekeeper when the lord of the manor dies. It doesn't sound like an equal life partner. B has "assured her," but has he actually sat down with her and made a financial plan that works for her and that she's on board with? Does she know exactly what assets she would have access to if B dropped dead? Do they have any joint accounts? Does B have any accounts where she is the sole beneficiary, like life insurance, etc.? What property will she own, where will she live, etc.?
4. Maybe she feels like she doesn't belong because she has a metamour who thinks she's kind of pathetic and cringe-worthy and in need of more therapy.
5. Adult adoption had a long history in the gay community before marriage was legal in the U.S. It's definitely a legal tactic people have used to create marriage-like relationships when legal marriage was not possible. Even going back to Roman times, adult adoption was a thing (not necessarily for romantic relationships in ancient Rome, but to secure inheritance and family status in Roman families). So, there is a legal precedent for it, and it could potentially be a valid option for a poly family. There is no reason to put quotes around "adoption" like that, the way people who are against gay marriage call it gay "marriage." It's condescending. Legal adoption may not necessarily be the right choice for K and B, but they should be able to look into it as an option.
6. I agree that adopting a romantic partner feels rather icky and I wouldn't want to do it. But it seems like you feel she is cringe-worthy for continuing to ask for a marriage-like status with B, like her whole relationship with B is kind of cringe-worthy.
7. I agree that I wouldn't want to sign onto adopting another adult myself, certainly not a metamour. But your tone sounds... harsh and unsympathetic for someone you supposedly consider family. No wonder K feels insecure. Can K trust you to help her if B dies and she's in dire straits?
8. The "we" in that statement indicates you and your legal husband, the "she" the person who feels like she already doesn't belong in your poly family. "We hope she feels more secure with therapy..." I don't know, this just rubs me the wrong way. Will therapy help K live the whole rest of her life with a metamour who finds her annoying and pathetic?
I know B is trying his best to love and care for K, and I'm sure K is a bit difficult and challenging. However, I wish K would find the strength to recognize that she is not happy in this arrangement and leave. I wish B would be a bit clearer or firmer with K about what he does and does not want to offer her, so that she can decide if she wants to leave.
And please recognize how much status, simplicity and relationship "weight" you convey with the luxury of being able to call B your husband (YOUR HUSBAND, as Bobbi put it), and how K can't ever have that luxury.