I'm trying to avoid using SQL here as I believe there should be a way to do this graphically
Why do you believe that? What's wrong with SQL?
As you surely found out (by searching SCN before posting your question, which I am sure you did 
) there is no exception aggregation in SAP HANA modeling. In fact exception aggregation is a concept that only exists in SAP BW OLAP...
Besides that, you did not tell us:
- what your base data looks like
- what your troubles with the grouping approach exactly are
- what your model looks like
Here's definitively some work to do getting the question right, I'd say...