私はワークを二度延長しましたが、プロセスを待ってる間は働いてましたよ。
弁護士を通してるし、移民法も明示してもらったので大丈夫だと思います。
SIN もとりあえず自動的に継続されるってことなので、6ヶ月間とりあえず放っておきました。
6ヶ月後にビザが下りた段階で問題なく更新できました。
以下参考にどうぞ。
If a temporary resident applies for renewal of their work or study permit and their permit expires before a decision is made, paragraph 186(u) and section 189 of the Immigration and Refugee Protection Regulation provides them the right to continue working or studying under the same conditions, pending a determination of their application for renewal, as long as they remain in Canada. This is referred as "implied status". The temporary foreign worker will have implied status until a decision is rendered by CIC.
In this case, a SIN card bearing a new expiry date will only be issued once CIC has rendered a decision. In the interim, where "implied status" is confirmed, the expired SIN may continue to be used. To obtain a replacement SIN card with a new expiry date, the temporary foreign worker must apply and present a valid immigration document issued by CIC.
http://www.servicecanada.gc.ca/eng/sin/employers/expiry.shtml