Report Builder - What section

Hi,

I'm trying to number actions on my list as 1.1, 1.2 etc, all relating to a section 1 in my smartsheet. I also have a handful of actions that I need to number as 1.6a and 1.6b etc. When creating the Report Builder however, the 'What' section doesn't seem to handle the letter, only the number, therefore any rows that have a letter next to the number in the 'Action number' column are missed. The column type is set as Text/Number. Any ideas?