It is a risk at any point to leave Canada and try to re-enter, whether she has been gone 3 minutes or 3 weeks. There is never a guarantee of re-entry and it is entirely dependent on the CBSA officer. A border run is a much more obvious attempt, hence the higher risk. I personally wouldn't leave at all while trying to establish common-law but that is your choice.So that just brings me back to the question I asked at the beginning of this thread.
Or is a border run deemed different that a three week stint out of the country? I’d do the border run with her.