Row grouping in table visualisation to help with one-to-many data

This would be VERY useful, I think. Example - one customer owns three products. The table visualisation has columns of customer and product attributes. The cells containing this customer's attributes are tall. The cells containing this customer's products' attributes are normal height. Stacked vertically, their combined height is the same as their adjacent tall cells. They are all part of the same single row in the table visualisation. Combine this with filtering and aggregates that can differentiate between 'owns this product' and 'owns only this product' and that would be perfect.