pb is sorta up in the air because she's only a half sister, but finley's dad is a scumbag and basically when he was living in the states with his wife in the early 90s, he cheated on his wife around the same time or shortly after he got his wife pregnant resulting in a child with another woman who he paid off her whole life until recently probably - neither girl knowing the other existed, until this all went down and the half sister found out about it all and reaches out/they live in the same area