They ask us to write 'not applicable' to confirm that the documents you submitted are fully completed and to make sure you didn't accidentally leave the space blank. According to IRCC, they may reject your application if they deem it is incomplete. But don't take my word for it.Reviewing my application after submitting and realized I left Section B on IMM 5406 (Family Information) blank as I have no kids. Also noticed they said to write "Not applicable" if a section doesn't apply. Does anyone think this would be an issue? I did fill out everything else for parents and sister though