Select multiple custom worksheet fields for charts Merged

We make use of the custom worksheet fields to track things like resource allocation or hours by a defined set of categories for releases and initiatives. The charting tool sees each field as an individual field so there does not appear to be a way to aggregate/sum/visualize several category fields into a single graph.

For example if the tags field is used to drive from, a pie chart can be created to identify the slices by tag of all the feature estimates within a release providing a visual for comparing how many story points were allocated to each tag or category.

Maybe a way to oversimplify is that if I were to create a list report with tags and original estimate, feature name, "tags" would be a single column. If I create a list report with a custom worksheet field, each field in the worksheet gets its own column so there does not appear to be a straightforward way to get all the fields into a single graph to compare or summarize.

However, I could totally be missing something obvious so there is that.