Looking for some guidance

I have a report that consists of multiple sub reports, where each sub report fetches its data via a web service call. Each web service call returns data about one or more items. When there is more than one item, I need to have all of the sub reports grouped by item, and I'm not sure how to go about doing this when designing the report/sub reports.

In other words, let's say I have items 1, 2, and 3. The current report will output something like:

Sub report A
data for item 1 (from web service x)
data for item 2 (from web service x)
data for item 3 (from web service x)
Sub report B
data for item 1 (from web service y)
data for item 2 (from web service y)
data for item 3 (from web service y)

The desired output is:

Sub report A
data for item 1 (from web service x)
Sub report B
data for item 1 (from web service y)

Sub report A
data for item 2 (from web service x)
Sub report B
data for item 2 (from web service y)

Sub report A
data for item 3 (from web service x)
Sub report B
data for item 3 (from web service y)

I would be very appreciative of any guidance.