Did the von carsteins know of Mannfreds existence? In Steven Savilles books he is not mentioned by name by any of his brethren even after Vlads death. Jon Skellan certainly didn't know who he was and Mannfred spends alot of the first book sneaking around not letting himself be seen by the family. Obviously Vlad must have known about him but for some reason didn't keep him around like the others.

re-read the last book, one of the characters knows exactly who mannfred is, the birds say over and over "mannfred is coming, mannfred is coming"