Fusion Aggregation

I'm trying to create a scenario that rejects a timesheet with hours marked on projects that are set to not mark time against them.  I am rejecting the timesheets and sending a message to them but it send a message for each timesheet entry.  When I try and aggregate to get one record per timesheet, It doesn't work because the timesheet ID is on multiple operations.  My aggregation is with in an operation. Is there a way to aggregate across operations?