Wow! I bet the bride regrets hiring her. That photo won’t really give her grandchildren an understanding of what Granny looked like when she got married!
I was going through YouTube and came across this: https://www.youtube.com/watch?v=4AoaNMWvfZE, the speaker was a news reporter that changed to portraits and weddings. His talk won’t fix everything that’s wrong with that photo, but it could help with the light.