How can I determine group with variable length paging?

I have a report containing 4 different groups. Each of these groups provide data in a different representation and need report header information to update dynamically.

Unfortunately, I can't use subreports with embedded hears, I also can't rely on page number to determine how to populate the headers. each group can be anywhere from empty to multiple pages in length. Does anyone have a suggestion of how I can evaluate which groups information to use?

Thanks in advance for any tips or suggestions!