why didn't they get a younger actress
One of the more realistic aspects of the movie was that they DID have 2 girls playing the daughter to show the passage of time and amazingly the older girl looked a lot like her screen mother Michelle Monaghan. That said, since this is supposed to be a biographical film, I would have appreciated a few dates giving us an idea when such and such occurred. Instead, everything appears almost intentionally vague.

I think a big part of it was that she was missing time with her dad. When she was really young, he was in prison. When he gets out, he's not there for her emotionally because he's still living the life. When he finds God, he becomes obsessed with Sudan and the orphans, and he's still not there for her. She's trying to fill that emotional void and trying to connect with her dad's friend, because he's there when her dad has, essentially, abandoned her.

They did. Duh, read the credits dumb ass.