Thank you for more info. I don't know if this helps you any. But I think this.
I don't get why you think you are "get along well" with your Meta, when she oversteps boundaries like this. It doesn't sound respectful of you.
Asking for help wording messages to me which a) is making meta feel uncomfortable (she has addressed this directly) and b) means the relationship we are building is less authentic, because they are her words not his.
It's on her to tell him "No, thanks. I won't be helping you word messages to other partners." Her inability to hold a boundary in the past is not your problem. Her addressing this directly now is still not your problem. Why did you even have to know about it? What was the purpose of oversharing this data?
It's on you to tell her, "No, thanks. Please don't overshare problems inside the (you + Hinge) dyad with me. I cannot be impartial. I'm inside the dating system. In future, I suggest you tell him that you will not help him do X."
On your side, you get to tell Hinge, "Meta made me aware that she helps you word messages to me and brought it up to you. I have no idea why she told me this stuff. I've told her to stop oversharing things from that side of the V with me. As for the messages, I expect you write them yourself. I'm dating you, not her. If you need help, you could use Google, ChatGPT, or trusted friends outside the dating system, not people inside the dating system."
Not being as considerate as needed to her needs (again she has brought up directly) ultimately means he is prioritising me over her and his family in a way I would never want him to do, and making her sad, which in turn makes me sad when I find out.
She doesn't like him asking her to do HIS message composition work to you. Now she wants YOU to do HER conflict resolution with him? Those two having weird personal boundaries is not your problem to fix or solve. Them having weird personal boundaries doesn't mean YOU have to have weird personal boundaries. Nip all this in the bud.
The one bringing you unwanted data and feelings of sadness is her.
I think you can ignore this one. Him not paying her enough attention is not your behavior to fix. The Hinge is in charge of his time and calendar. He can learn how to hinge and figure out how to balance time with each partner.
If she brings it up to you again, that's where you get to say "No, thank you. I'd prefer you solve (you + Hinge) problems directly with Hinge, not involve me or overshare. It is not appropriate behavior."
Voicing opinions about Meta's other potential play (to her, but she was explaining to me, so now I know those opinions, even though they haven't been said to me directly). These are big red flags to me, in terms of competition, and also trigger my own insecurities.
Meta not liking Hinge's opinions about Meta's other potentials... why on earth would you have to care or get involved in all that? Why did she have to "explain" them to you? Why do you even have to know? What is the purpose of telling you all that?
Again, this is where you get to self-advocate and tell Meta to STOP oversharing.
If this Meta is oversharing (Meta) stuff or (Meta + Hinge) stuff with you, treating you like a confessor, free therapist or emotional dumpster, and you don't like it you say "No, thank you. I'm not up for this kind of talk. It's not my business. Stop oversharing. Please respect my limit."
If she keeps doing it, you ask her why she doesn't respect your limits, and/or go parallel. There is nothing wrong with separate, parallel poly. You aren't dating her. You don't have to be friendly with people who don't respect your limits, your time, or your energy. You can stop chatting/hanging out with her. Put some distance in there.
And if that's still not enough separation, you dump him so she's not your meta any more.
YOU get to decide how close you want to be with people. YOU get to decide what is and is not acceptable behavior towards you. YOU get to decide what you will and will not tolerate from people.
Galagirl