I resolved the issue. Sometimes it just takes taking the time to document the issue and then posting it, because the answer came as soon as I saw it posted. I right clicked in the first grouped column; added a parent group and grouped that [SPRSNSLN] and sorted it with the same sort expressions as the Detail group and viola. The salespersons are now showing their individual top 50s within each branch.

Sometimes, I just need to see my own work from a outside perspective. 😀

I hope this helps someone in the future.