i can't open the form unfortunately, however it says right on the checklist:
if you (the principal applicant) have more than 5 dependants to declar, please use the following form to continue your declaration: additional dependents/Declaration (IMM 008DEP). if thoes not apply to you, you do not need to complete this form.
does the principle applicant have more than 5 children to declare in the application? if not, then it doesn't apply to you.