That's just it. Tieflings aren't tribal about Tieflinghood. They're lumped together but apart from lineage, have little in common. Not a strong community. They look like they'll disband should they reach BG.
Asharak, Wyll, granny cook, Rikka and the bard collectively look after them. But apart from Rikka and Doni there's no caring adult/child bond. Guess that's the space Mol fills.
I think you are forgetting that half the Tieflings are lined up outside the ceremony trying to get a kid back, including her parents.
True. I had been thinking about the orphans rather than all Tiefling children. I'd say Arabella's parents had a big say in getting a crowd gathered.
I note that neither Mol nor her orphans were protesting either, not that that would be wise. But still, you'd think they'd be more interested in one of their own getting caught than running scams.
