A CIC lady sent me an email with instructions how to update any personal information. Here it is (I mailed my CSQ by regular mail using General Mailing address from below):
Sir, Madam,
Thank you for contacting Citizenship and Immigration Canada. I am pleased to follow up on your request:
Update Personal Information - CPC Mississauga
To update your personal information while your sponsorship application is in process, you can notify us by using the appropriate email template listed under the How do I contact CIC? section on the website.
An update in your personal information could include:
A change in marital status,
The birth of a child,
Criminal charges against you,
A change of employer,
Etc.
In your email, please provide the Sponsor's:
Name,
Date of birth, and
UCI Number/Application Number.
If you are unable to send your information via email, you can mail/fax it to the Case Processing Centre (CPC) in Mississauga, Ontario. Please find below the contact information for the CPC:
General Mailing address
CPC Mississauga
P.O. Box 6100, Station A
Mississauga, ON
L5A 4H4
Courier Address
CPC Mississauga
2 Robert Speck Parkway,
Suite 1200
Mississauga, ON
L4Z 1H8
Fax: (905) 803-7392
If you change your contact information, you must let us know immediately through our Online services.
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Note that you only have to mail the copy that states "IMMIGRATION-CANADA" on the bottom. The other copy you'll need for requesting health insurance.