Usually grouping is used to group the data together by criteria. Generally speaking different data sources deliver different data so I guess that the best solution is to use subreports. The 1st CTP version does not have such report item but for the final release we will provide one. Using the subreport item you can embed several different reports in one report. Different reports can use different data sources and you can arrange your “master” report to look exactly the same way as a report with groups.
About the textboxes – now we are working on item events that will allow you to control the item behavior at runtime when binding and printing items, and I think handling these events will help you achieve your goals.
You’ve missed to tell us what viewer you’re using to print the reports but I think that with the win viewer you can choose whether to print the whole report – all pages or current page or only some of the pages.