Principal residence exempt from capital gains?

Hello - in 2017, I began renting our 2/3rds of my principal residence.  I declared a deemed disposition on my 2017 return for that 2/3rds portion, due to the change in use.  In 2018, I left the remaining 1/3rd of my principal residence and began renting that out as well, moving in with my parents, temporarily, where I currently still live today.

I spoke with the CRA, and the rep indicated that on my 2018 return, I could elect under section 45(2) of the Income Tax Act to have my entire property deemed my principal residence, because the whole property is now being used as a rental.

Assuming that to be true, and if I take that election, I am attempting to figure out when I would pay capital gains on various portions of the property under the following scenarios:

Scenario 1: I move into a new property in 2019 and make that my principal residence, keeping the other property as a rental (hereinafter “the Rental”).  In that case, I think I would eventually owe capital gains on the 2/3rds of the Rental, from the time I rented it out in 2017 to the time I deemed it my principal residence in 2018, and then I would also owe capital gains on the entire Rental from the time I began living in the new property as my principal residence.  I would then pay the capital gains for those periods in the tax year when I actually sell the property.

Scenario 2: I move back into the Rental in 2019, kick out the renters and make the whole property my principal residence.  I make the election under section 45(3) of the income tax act.  In that case, I think I would owe capital gains on the 2/3rds portion of the Rental, from the time i rented it out in 2017 to the time I deemed it my principal residence in 2018 (although I also noticed that under 45(3), a person can shelter the property from cap gains up to 4 years before moving in, so perhaps I’d owe nothing?).  Then, if I moved out again into a newly purchased property and began renting out the Rental again, I would also owe capital gains on the entirety of the property from the point of moving out, up until the point of sale.  I would pay the capital gains for both periods in the tax year that I actually sell the property.

This is my best educated guess on the matter; however, I would greatly appreciate the community’s input on both scenarios.