I don't really get what you said.
In maffia and yakuza, unrelated ppl get called 'brother, aniki' stb. There were the previous boss of the wolf who died, his death-anniversary were right now.
The wolf and the enemy (potato's dad) were once working together, and the so-called brother got killed by that enemy (potato's dad).
I think.
A-Bao is his boss' biological son and Wolf King is his heir. Hence, the fight. It's mentioned in one of the earlier chapters (before they discovered Potato's identity). The boy who was murdered Wolf King's adopted younger brother. They are now at Potato's grandpa's funeral.
But Potato himself is illegitimate and was "discarded" by his dad so fuck that guy either way. P.S. I dont think grandma knows of Potato's existence.
So potato is the son of the man who killed his brother and they are at whose funeral rn. Is it potato's father or potatoes father’s dad who would be potatoes grandpa’s funeral??