The UNION query just creates the field that can be used as a grouping criteria.
Use the UNION query as source for another query that does the aggregate calcs.
See post24 where you quote my earlier post. I show an aggregate query as the pie graph RowSource.
SELECT Category, Sum(Hrs) AS SumHrsCat FROM UnionT1 WHERE (((UnionT1.Tech)=[Forms]![Par-Pak final].[Technician Name])) GROUP BY Category;