They will read your report out and you will be asked by the chair "do you have anything to add or change"? The ONLY possible answer is NO, as if you say yes and provide details the very obvious question that will come back is "why isn't it in the report then?"
Other than that, as James has said, you are just giving evidence. The player and his reps will probably tell a pack of lies, but just stay calm and don't rise to it. A well trained panel will ask the right questions to tease out what actually happened, if they don't and they believe the lies being told then just remember that isn't your problem. You have done your job on the green stuff and with the paperwork after.