• I think you should be able to do this using groups. Each sub-group can have its own columns, and you can toggle their visibility off of the groups above them (in Groups Visibility - set the subgroup to Hidden, check the "visibility can be toggled" and select the group above). Note that you do this in the group properties, not the row properties.

    You can have fewer columns in the totals group by either merging cells or just not using all the columns.