At mediate.com Dave Ezra provides good advice on writing to persuade mediators and other participants in mediation. He starts: "In many cases it is the mediation briefs -- the overlooked briefs that are often hastily prepared at the last minute -- that are the most important briefs."
"Remember one thing -- mediators read the concluding sections of mediation
briefs. Some might even read them first, before they look at any other part of
More on Written Position Statements in Mediation here