Usually it is the elderly unifying, but in our case it’s the reverse.” (Erich)
“Erich is intelligent and Wend can use magic.” (Paul)
Having together experienced the pain of not succeeding a household, it seems that fellow siblings, who left their home, have a tendency to gather.
But it appears that there were many cases where such relations broke down very quickly due to the other siblings luckily marrying into a noble family and thus becoming nobles themselves or due to becoming successful in life.