Instead of one protagonist, rotate the point of view. Episode 1 is the eldest daughter’s perspective; Episode 2 is the father’s. This forces the audience to rebuild their moral compass with every chapter. A decision that seemed "evil" from one angle becomes "tragic" from another.

The Twist: Instead of making them outright enemies, make them fiercely protective of each other against outsiders, even while they tear each other apart behind closed doors. Parent-Child Friction

A character who cut ties years ago suddenly returns. Their presence acts as a catalyst, forcing the family to confront the original trauma that caused the rift. The Enmeshed Family