Hi X BOX,
Don't do that, unless you accompany your sister you cannot let her carry your Passport. It is an offense, even an authorization letter will not suffice. There will be a lot of explanation to be done if checked or caught. So please seek an alternate opinion.
The only work around for is to change you are address by Mailing to (OttPilot-Immigration @ cic.gc.ca) as mentioned in the below link
www.cic.gc.ca/english/information/offices/canada/ottawa.asp under FAQ no 3.
Please e-mail us (OttPilot-Immigration @ cic.gc.ca) in any of the following cases:
You change your marital status
There is a birth or death in your family.
You change your mailing, residential or e-mail address if you reside outside of Canada**.
**If you reside in Canada, you must use the CIC's online form to change your contact information.
It is up to you to keep your contact information up-to-date. If you do not keep your contact information up-to-date, it could delay the processing of your application. Please quote your complete application number (letter “E”, “EP” or “F” ) followed by eight or nine digits in all correspondence with our office.