Unfortinatly you are right
Sonnia, Tara, Mei Feng are in the first book the rest are in the 2nd (3rd book does not have masters)
Personally i suggest Tara as she really does not need a thematic crew to work at all, can hire death marshals (in my opinions one of the coolest models). I usually run her more freicorp than her own list. Also on the lore side the void stuff is this weird pieces of nothingness which are not spirits upside is the cant drop corpses if you are facing resser players.