What is required to move seasonal US belongings back to Can

I have offered to move my aunt's household contents of her Florida winter home back to Canada for her. She has sold her home there, and is flying back to Canada. My brother in law owns a Cube Van, which I intend to drive to Florida, and return with select contents.
What will I need to do to cross back into Canada without duties/taxes, or aggravation?

There are customs forms she'll need to fill out for all her stuff. I can't remember which form numbers they are, but have a search at the Canada border services website. http://www.cbsa-asfc.gc.ca/

CBSA Forms B4 and B4A.