Who are the Frohn family in WiAB? I don't remember that family name
The MC in WIAB sees and speaks to one of the Frohn girls, who doesn't answer, at the bar in Relucia Dinner. (The blonde Frohn with bobbed hair looked rather like Maja to me.) And at the physiotherapy centre in SG the physiotherapist Celina addresses both Victoria and Maja using the surname Frohn, i.e., both girls are probably blood related members of the Frohn family (who seem to be rich and wealthy through speculative business dealings and investments in stocks and shares).
(Unless one or both of the girls have been adopted or married into the Frohn clan, the latter unlikely because Celina addressed Maja as "Miss".)
So it looks very likely that characters belonging to the Frohn lineage are present in both VNs. The two VNs seem entangled spatially but maybe not temporally, i.e., the where might be the same but the when different. We will all just have to wait and see as the smouldering slow burn world building, saga unfolding and mystery revealing evolves deliciously over time.
(Which I for one am totally cool about and can't believe how invested in these story-worlds I obviously have now become!)