Bogan's great-aunt isn't named but does appear, I think; she is (presumably) the very old lady chaperoning him:
>Visibly terrified at the prospect of going forward with the
>day's agenda. He wouldn't even look her in the eye when her grandmother
>and his own chaperone, an elderly woman who (unlike Duchess M'belyyn'da
>the Elder) really did qualify for the title of "crone", had introduced
And I'm not sure I'd be entirely quick to judge here. Umi's family got out of Hyeruul; the Duchess attempting to drag them in is kind of a dick move. But everybody else has to live there, and Hyeruul seems like a pretty patriarchal place. That means if you're a woman, there are only a few paths to wielding real actual power and having a degree of control over your own life, and this is going to be one of them.
I'm reminded of a quote from one of Charles Stross' works, the Clan Corporate, about how that kind of intergenerational dysfunction can work:
"Look, the rules are really very simple. You grow up hating and fearing your grandmother. Then she marries you off to some near-stranger. A generation later, you have your own grandchildren and you realize you’ve got to hurt them just the way your own great-aunts and grandmother hurt you, or you’ll be doing them an even worse disservice; if you don’t, then instead of a legacy of some degree of power all they’ll inherit is the status of elderly has-been chattel."
The Duchess at least can wield power in her own right as a widow. Bogan's great-aunt might not even have that going for her.