Here is some background info about my relationship with my girlfriend. 6 years in total, only 3 of them in Canada. We both came from different countries. We lived in BC in the same Host Family for the first 2 years and then we rented one apartment using both our names. About 3 months later I started applying for my PR through the CEC branch.
After sending my application, the only LEGAL document proving me and my girlfriend were living together in this Canada is was that contract for the apartment rent. We had no contract in our previous host family, and even though we were living together, there is no proof of that, other than mail sent to same address (so what, the host family had more guests in there?)
By the time I received my CPR, we didn't even made a year living/cohabiting in the same place, so I guess we were NOT common law. It was only after I got my PR card when we both were living in the same place, with a real rent contract showing both our names.
In simple words, there is no strong/legal proof we were common law other than that contract. So technically, I could not add her to my application.
If you become common law partners or get married after you become PR, couldn't you sponsor your partner/wife later on?