As per Section 16(1) the Immigration and Refugee Protection Act states:
- 16 (1) A person who makes an application must answer truthfully all questions put to them for the purpose of the examination and must produce a visa and all relevant evidence and documents that the officer reasonably requires.
If you have been in a CL relationship, you have an obligation to disclose it and add your CL partner to your applications. If this is later discovered, that you were in a CL and did not disclose it, that is a misrepresentation. However, CL is shy of being married and how you see your relationship is entirely to you. This is more of an issue in sponsorship cases.
You can read more on this
https://www.canada.ca/en/immigratio...lass-determining-spouse/assessing-common.html
IMM 5409 has to be attested by a notary, commissioner for oaths.