I love the way Learn 2 Live breaks it down here. I, too, have an AB and family and they make some funky choices. Queen Codie, my mom, tries to 'make peace' and sometimes she'll invent some things to make peace about, even when there is already some semblance of peace.
I have always been cautious of having any type of 'power' over my siblings, as the oldest. I think it's wise not to feel any superiority or self-righteousness over your position in the family or in your father's trust in handling the family business. This is a common codie pawn. Codies are very susceptible to passive manipulation.
You should make amends for anything you participated in that caused the drama. But that's for you, not your dad or anyone else. That's your part of this. The rest? Let it go.
I think you should thank dad for his trust in you and let him know you will be there for him in other ways.