Hi Wheeliea,
One simple way to do this is to add an receive data connection to an XML file that has three fields in it:
<viewState>
<field1></field1>
<field2></field2>
<field3></field3>
</viewState>
Drag the secondary data source values to each view - one for field1, one for field2 and one for field3.
Add a rule to each field to set a value. Specify the value of the repeating node in your main data source.
This doesn't quite work since you aren't indexing it.
You'll have to go into the manifest.xsf (File->Publish->Export Source Files) using notepad and add the [1] or [2] or [3] index after the xpath for each of the three rules.
Then it will work.
Of course, it's slightly more complicated if you have a lot of fields in the repeating child group, but you can do it.
Make sure your main data source looks like this:
parent (non-repeating group)
child (repeating group)
fieldA (non-repeating)
fieldB (non-repeating)
...
Good luck