if it is all in the same group, you could probably do that, suppressing the details and displaying the results in the group footer...but cr doesn't allow you to just loop through the data in a controlled way.
If you have a middle tier in your app, you can use that to do the looping and build a recordset of what want and pass it to CR...
or you could use a stored proc...but since it sounds like you are already getting a file, I would try the middle tier approach first as it will be the most flexible.
HTH