You mention the checklist. The only question pertaining to the OWP on the checklist (IMM5533) is question 5. As you’re inland you need to select the first checkbox which states ‘I am currently living in Canada with my sponsor, and I am applying under the spouse or common law partner in Canada class’ and ensure you check the box underneath the mailing address which states ‘I am also including an Open Work Permit application’. As you’re inland the two checkboxes underneath this (living outside of Canada and Inland Family class but not spousal) do not apply to you.
Is this the part you were referring to or are you having issues with the OWP form? (IMM5710) if so, which questions?
Hope this helps!