Assuming you currently rent right now, and you are buying the single SFR as a primary, the 3-unit should just be designated as investment and you should be able to use the rents to offset the payment (up to basically 'zero-ing' it out, on paper). 

Built in 1905, this property features a total of 2,832 square feet of living space, divided into two units.

If you really want to get rid of them, sweeten the pot by offering to return their deposit after you verify the unit is empty with no damages. 

Try to get as many units in the building as you can.To Your Success!

You should consider getting the most units (that can rent for the highest) for the best price.

Aside from what everyone else wrote, note that adding units require various steps that you may not have considered (e.g., adding a new street address with USPS, etc.).

HiWhen we started out we bought a multi family property and lived in 1 unit.  

@Albert Gallucci as many have pointed out, in the commercial space of 100+ apartment buildings and offices, property classes have some pretty decent industry standards.We started applying these to 1-4 unit properties around 10 years ago, which you can verify on our blogs, because we saw too many newbie investors not properly taking into account things like, neighborhood status, tenant pool, property condition, etc.Unfortunately, there's no industry standard for this, but you can use some basic logic to think your way through your own Classifications.

Once you take over a property as an owner occupant, if it is a single family or condo you can live in it for 1 year and that automatically exempts your unit from rent control.

. - Another exception to note on that foreign buyer ban is the number of units/doors for your investment: I believe the magic number is 5+ as this would be considered as commercial Real Estate- In Ontario, you will also have to look our for the Non-Resident Speculation Tax (NRST) which imposes about 25% on the purchase tax.