You need to set-up a logging rule in the MWG config to put a special value in log record for coached traffic. Then assign that new column to a user-defined column under the log source configuration in Web Reporter. I'd recommend you log a value that you want to show in your reports. User-defined columns are all strings and have no numerical value. While you could log numeric values, then have Web Reporter translate them to more user-friendly terms, you're off loading the problem, and better to take care of it on the MWG side.
I'll defer the MWG configuration to someone more qualified in that area. But you just need to pick any column name that isn't one of the defaults Web Reporter uses.
Sorry, E-squared just reminded me that my explaination probably wasn't too clear so I'll elaborate.
Web Reporter only maps MWG logs into block and allow actions, so it's impossible to get coached sites separated. If you want to report on coached traffic, the only way to do it is with user-defined columns. And you cannot use the block_res column since it's treated special by Web Reporter. You could use it, but then you would need to rename it to something else, but then you wouldn't see any blocks. So really you would want to double log it under a different name, and keep block_res in place.