Don't have a lot of time, so some brief thoughts/observations on Meng Diu. At court she didn't seem that hostile to us, despite our fairly poor standing with the Meng. It's entirely possible this was due to the fact she's an Indigo cultivator and has great Poise.
However, it might be that applying the platonic ideal of Meng-ness to Meng Diu simply doesn't make much sense. The stereotypical Meng is, well, kind of like a Bai-lite. Isolationist, traditional, elitist, and disdainful of younger clans/establishments. Meng Diu specifically has an ambassadorial role to the provincial court, so we could assume she's somewhat more sociable with outsiders than the norm. It's literally her job. Her being a bit less reflexively critical of things her kin normally would be isn't an unreasonable assumption to make, though also isn't confirmed.
Basically, this lady could be relatively friendly for a Meng. She's also got decent clout in the clan between her cultivation and relations, so it's a good opportunity for us. It also does mean, however, that this could be a personal project of hers rather than something directed by/for her clan as a whole, per se. She has the leeway to look into things on her own initiative.