Canon LBP7210Cdn Manual page 321

Specify the printing preferences in each sheet, then click [OK].
The [Print] dialog box reappears.
Click [OK] or [Print].
The list of jobs are displayed in the [Canon PageComposer] dialog box.
NOTE
Specifying the setting to always display the [Canon PageComposer] dialog box when
performing printing
Set [Output Method] to [Edit and Preview] as a default value for printing preferences, and then
select the [Lock] check box.
For details on the procedure for changing the default values for printing preferences, see
"Changing the Default Values for Printing
Repeat Step 1 to 6 to combine the desired jobs.
Combine the jobs.
Preferences".