Bagaba and his annoying brothers

[Lex]

I did more tests today. I can not get "coin / shop" symbol over Bagaba's (middle brother) castle even when I am finishing this series of quests by doing them "normal way" i.e. by not attacking Squelch and putting his flag over youngest brother house. And yes, my tests also included finishing additional quest from Bagaba, Dirty Butory's Debt.

Now I am really interested in how it is possible to get coin mark over Bagaba's castle like Gatts said in his post?