It's not applicable in Spousal Sponsorship applications. Therefore, you can safely ignore it.
Q101) What is co-signer? Are there any Co-signer in Spousal Sponsorship application?
Co-signer sections
If you are sponsoring your spouse, common-law partner, or conjugal partner you can’t have a co-signer. Leave the following sections blank:
Q102) What is 'De Facto Spouse' in Quebec?
De Facto Spouse (conjoint defait)
[Similar to Common-Law Partner] A person 16 years of age or older of the same or different sex who:
This term is specifically used in Quebec which is equal to "Common-Law Partner".
Source(s):