Before I get a whole lot of hate for this, please know that I do not like this data-set either. It is overly-complex and commits a lot of design sins. Nevertheless, it is what it is for now and I still have to use it.
Also, the data I am trying to output in this report is also annoying, because the consumers of this report want to export to Excel and keep the data types as they want them, which are different per row (yep, row... not column - FUN).
Anyway, I have everything solved with this data set except for one problem... I cannot make the parent-grouped data appear on every row, it is always merged. I managed to change the first column, by creating a set of fields outside of the primary group, but now every subsequent row is merged, which just pushes the problem down the line.
Anyway, here is the layout of the report, I have blown out the margins and changed some colors so you can see it better:
Now, the portion of the report that I have colored yellow, is an outer tablix, used to tab the inner tablix within Excel, based on ElementDefinitionName.
The orange portion of the report contains the groupings found within the graphic. This currently produces output similar to this:
Any help that I could get with this would be greatly appreciated.