I was exactly in the same situation. I raised a webform notifying IRCC about the change in my family composition (addition of outland spouse). I am copy-pasting the response I got from the visa officer:
"If you are the principal applicant of a permanent residence application already in process, you could add your spouse or common-law partner, dependent children, and their dependent children to your application, even if they were listed as a non-accompanying dependent in the initial application.
To do so, we invite you to send your add-on request through the IRCC webform available on our website. You can attach the following forms and documents in the field reserved to that effect:
A new Generic Application Form for Canada (IMM 0008) with supporting documents,
(If applicable) A Schedule A - Background/Declaration (IMM 5669) form,
(If applicable) An Additional Dependants/Declaration (IMM 0008DEP) form,
(If applicable) A signed Additional Family Information (IMM 5406) form,
A copy of the birth certificate, marriage certificate or proof of common-law relationship,
A copy of the family member's valid passport,
Police certificates for all countries where the family member over the age of 18 has lived for more than 6 months since turning 18,
A letter of explanation, and
If applicable, the proof of payment."
I hope this helps! Good luck.