For years I did not have a backup shooter. My wife now is my backup shooter. I finally talked her into it a couple of years ago. She refuses to learn the technical side of things so I just setup a camera with flash bracket, 580EX and omni-bounce. She shoots lots with a keeper rate of ~30%. She has an eye for things that I sometimes miss and ends up with some great shots. If there is a balcony I set her up with a camera on tripod during the ceremony. I am sure your daughter could do the same if willing. Just tell her to shoot everything. When shooting posed shots my wife helps make sure hair, jewelry, etc... is straight and looking good. I am sure your daughter can also help here as well.