Sponsor common law partner while being married

[Youthberry]

Hi guys,

On the CIC website, it says that a person can sponsor his/her common law partner while still married. The person will need to provide evidence the marriage is broken down.
One of the evidence option is:

• a signed formal declaration that the marriage has ended and that the person has entered into a common-law relationship

Does this mean we just need to go to a notary to declare it? (We also have other evidence, such as tax returns filed in different provinces before and after the separation)

Because it takes so long to reach to the ex-partner to file the divorce, we hope that we can submit the sponsorship application before filling it. Would this be alright?

Thank you in advance.