Thanks for that answer .
In fact for now we have 2 options (flights cost are more or less the same, direct flight from Montreal)
Options 1) leaving july 9 from Montreal to Barcelona (arrival july 10) return august 2 from Lisbon. That makes 23 full days in Europe
Option 2 ) leaving July 4 From Montreal to Lisbon (arrival july 5) return july 26 From Porto . That makes 21 full days in Europe. In that option we would rent a car after Lisbon going up to northern Spain, stopping on route in different places in Portugal (the farthest we would go is San Sebastian) and finish our trip In Porto.
Still debating what the best option is.