Riversdale's older housing stock means past renovations may not have been permitted, and public records cannot see that gap, which is exactly where an online estimate tends to undervalue or overvalue an inherited property.
The Canada Revenue Agency treats the property's value at the date of death as its cost base for any capital gains calculation, so a documented valuation near that date is worth keeping on file for the estate.
Confirm legal authority to sell first, then get a walk-through valuation rather than an automated one. Get your hand-reviewed valuation from Joel Dyck.