My daughter and I thought it was a good idea to write a book about our experiences throughout her casting for a movie that she did. Her view on the journey and My view as her mother. Not sure how to structure it so that it's clear to the reader. So far we've been writing it entirely as her with her just stating things like my mother thought blah blah blah but I feel it would be better if it was first person from each perspective. Sort of the way the showtime drama 'The Affair' is done. Any suggestions or examples?
I'd say that splitting it by chapter would be the most logical approach. However I think that only works if you are telling a story in your own right. So the reader reads a chapter from her on one aspect, then gets another chapter on your views on that event.
You would need to be quite careful how you choreographed them, you wouldn't want to bore the reader by repeating everything. You'd need to divy out the crucial story points and decide which one's furthered each character's story the best. It would certainly be a challenging thing to write, but I imagine quite fulfilling.
If you are simply providing a commentary on her story, then maybe footnotes, or occasionally interspersed pages might be better (with a big 'mother's thoughts' at the top!)
The first step is probably to sit down and decide what you want to write, what you both want to contribute to it, and what you want the end product to be. Once you've got that, create a story plan between you, with a concrete idea of who is saying what.
Other than that, it sounds an interesting idea, I wish you luck!
One approach is to write separate chapters (maybe alternating, but maybe in this case more from her?) with the writer identified at the beginning of each. A similar approach was taken in the Jumper novels by Stephen Gould; each chapter is "titled" with the name of the point-of-view character for that chapter. I once read a novel, I think by Spider Robinson but I might be mistaken, where two characters alternated chapters in first person; that would be similar to what you're describing.
In both of these cases the change in point of view didn't impede the story; that's really important. What you talk about in one of your chapters should follow naturally from whatever she talked about in the one right before it. Don't jump around; that'll confuse your readers. (Consider how confusing it is to read a comment thread where people posted out of order. You don't want to cause that kind of reaction in your readers.)
Remember, as the two of you plan this, that not all chapters need to be of equal length and you don't need equal numbers. If it seems more natural for her to have more of the text, do that. If it ends up being closer to 50-50, consider alternating.