SSRS – How to Add a Column Group to an existing Table

You have created a table (tablix control) in SSRS which is working well however now you want to pivot the dates along the top of the report (column groups) to analyse your data over a Year – Quarter – Month hierarchy.    You can either drag a matrix control onto your report at this point and start from scratch however this will lose all the nice formatting and expressions you have put into your table.

Nice solution to the problem demonstrated Here.