Principle home or investment property

My client sold half share of the principal home to her sister in Mar 2020. The Client has another property (was on rent) and now she is building a new house in the 2nd property and will make it her principal home (when ready to move in). So far she is still using the first house as the principal home. How will she report the sale in the 2020 tax return? is she able to claim this as her principal home as she is still living there?

“Principal Residence” definitions are found at
ITA Section 54

Additional reading is at Folio S1-F3-C2,
(Income Tax Folio S1-F3-C2, Principal Residence - Canada.ca)