You will find some information here:
http://www.cic.gc.ca/english/resources/tools/perm/express/refuse.asp
From the website,
All family members must be examined as part of the e-APR, whether they are accompanying the principal applicant or not. Family members
can be added to the application at any time during the process, including after the visa is issued, but prior to obtaining permanent resident status. Applicants are instructed to inform CIC immediately if their family composition has changed (e.g., birth of a child, marriage, divorce).
Pursuant to subsection R4(1), the principal applicant may not include a spouse or common-law partner in their application if their relationship was entered into primarily to acquire any status or privilege under the Act or is not genuine. Similarly, in accordance with subsection R4(2), the principal applicant may not include an adopted child in their application if the adoption was entered into primarily to obtain any status or privilege under the Act or if it did not create a genuine parent–child relationship.
Section A11.2 does not apply when an applicant adds a family member to their application after the e-APR; however, the family member will have to be assessed, and the principal applicant must provide CIC with the Additional Family Information form [IMM 5406 (PDF, 570.00 KB)] and pay the applicable fees online.
To inform CIC, you will need to send a Case-Specific Enquiry form
https://secure.cic.gc.ca/enquiries-renseignements/canada-case-cas-eng.aspx
You'll need to complete the Additional Family Information form and pay the fees before informing CIC. You can attach the form and payment receipt to the CSE. Your spouse will be required to do a medical exam and submit a police certificate as well. I am not sure if this is before the CSE is sent or after CIC receives the CSE. Maybe others with more experience can confirm the timeline and documents required.
I hope this helps!
