Briggs/McRae Marraige - What will these clues reveal?

As I am reviewing the information I have so far I come across a note I've written that says "Rufus Briggs--uncle down the street". My grandfather told me his half brothers uncle's name was Rufus Briggs and he married a school teacher named Miss McKoy. I searched for and found their marriage record however the only information filled in was their names..no dates..no witnesses. As I was browsing I found a marriage record for Joseph Briggs and Anna McRae. My heart skipped a beat when I saw one of the witnesses was J.E. Womack who is my great-grand father.

Sallie Briggs was my great grandfather's first wife. Martha McRae was my great grandfather's second wife. Since Sallie and James (sometimes Ed)last child together was born in 1907 I don't think Martha and James were married yet. Was James their in support of Joseph Briggs (possibly Sallie's brother) or Anna McRae (possibly Martha's sister)? I don't know what happened to Sallie Briggs and I've always presumed she died between 1907 (the year her last child was born) and 1910 (the first year Ed and Martha are listed as husband and wife on the census). Went back and took another look at the 1910 census and discovered Ed and Martha had been married for one year according to the information on the census. While I am curious about Sallie Briggs my focus is on Martha McRae. According to the information I have Martha was born in South Carolina. I don't know who her parents were or if she had any siblings. What will the information on the marriage certificate reveal? Is it possible Anna, Martha and Peter (another witness at the wedding)are siblings? I'm on a mission to find out!!