Is there a maximum number of boxes? There are only two ways that I know of to do this:
1. Have a query that returns a row of label data for each box. Put the label in the details and suppress all other sections. Turn on "New Page Before" on the details with "PageNumber > 1" in the New Page Before formula so that you don't get a new page on the first page.
2. Create a set of details sections - one for each possible lable (this only works if you have a reasonable maximum number of lables!) Copy the label format into each detail section. Selectively suppress the sections based on the number of boxes in the parameter. For example, for the second label, section you would put something like this in the suppress formula:
{?NoOfBoxes} < 2
For the third:
{?NoOfBoxes} < 3
etc.
You would also turn on "New Page Before" for each detail section except the first one. A new page won't be generated for a section that is suppressed.
-Dell