"This documentation is required if the applicant indicates that they, or their spouse or common-law partner, have a family member in Canada who is a permanent resident or a Canadian citizen.
A copy of both sides of the family member's Canadian citizenship document, Canadian birth certificate and/or permanent resident card must be provided.
Evidence that the family member currently resides in Canada must be provided (a residential lease, mortgage documents, utility bills, etc.).
The documents should be up to date as of six months prior to submission.
Proof of the relationship of the applicant or the spouse or common-law partner to the family member must also be provided (e.g., a birth certificate, an official document naming the applicant as a parent, a copy of the inside back cover of the relative’s passport showing the relative’s parents)"
http://www.cic.gc.ca/english/resources/tools/perm/express/intake-complete.asp