How can I establish a sync between two different groups in one table of custom print?

I am trying to prepare a table in the custom print template for Comment History( which will contain all general comments with its corresponding date, step name & commenter's name) . As data elements for step name and comment details belong to two different parents, I did two groupings accordingly. But please help me stablishing a sync between these two groups so that I can see the respective step name for the each general comment.