I don't think that set analysis will help you with this. You will need to create a derived dimension field in the load script (preferred solution) or create a calculated dimension which will be complex due to the differing granularity in the chart.
For more specific help, you need to provide a lot more information. The best option is a sample QVW containing relevant data and the chart. This document should load from inline tables, or else you will need to also supply some source data in a text file, excel or qvd so that the changes to the load script can be tested.
Logic will get you from a to b. Imagination will take you everywhere. - A Einstein
