If you have many more than 3 or so, there are other ways you might want to explore. One would be to start with a query that returns the names of all reports whose checkbox selection is set to True (checked) then loop through a recordset and print out each report. Checkboxes or radio buttons or command buttons on a form could accommodate your needs, but it is a clunky way of providing the input. Each time a report is added or removed from the db, the form has to be redesigned (not good).
If there are only a few reports, then a listbox whose multi-select property is set to true would allow you to choose several reports. AFAIK, combo boxes still do not have a multi-select property (and I would not resort to using a multi-value field to get around this). You could also loop through the selected items in a listbox, and the list would be generated by looking at a table of reports.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.