Radio buttons are intended to select only one item. For multiple items you need check boxes. Personally I wouldn't use a template, but create a macro that reads the required information into a VBA userform multi-select list box, from which you could select relevant items. You could have a two column combo box for the managers' names and e-mail addresses and text boxes for the date and file number.
It is then relatively simple to create a message containing the required information based on the selected items from the userform.
Although aimed at extracting message information to Excel, the principles of extracting message data are described at
http://www.gmayor.com/extract_data_from_email.htm