you should send it together:
"Maintaining a Legal Status During the Process of the Permanent Residence Application
When you are in Canada, you must always keep a legal status until you become a permanent resident. If you do not, you could be removed from Canada. If an immigration document was issued by Citizenship and Immigration Canada (Work Permit, Study Permit or a stamp in your passport), this document states for how long you can stay in Canada. Having a legal status means that your document or authorization to stay in Canada is still valid.
You have two options available in order to maintain a legal status in Canada until you become a permanent resident:
Depending under which immigration program you apply, you could apply for an extension of your status as a visitor, student or worker, while applying for your permanent resident status. If you choose this option, complete both an application to extend your status and an application for permanent residence and mail them before your current status expires. Be sure to include both applications and all the necessary supporting documents and payment for each application in the same envelope.
If you stay in Canada during the processing of your application, you will only have to extend your status once because this option will allow you to keep a legal status in Canada up until the time your application for permanent residence is *approved in principle. If your status expires before your application for permanent residence is approved in principle, you will still have a legal status in Canada. This is known as implied status."