As others have noted...e-fares do impose somewhat of a minimum stay. Flying from WAS, I know that I can select either a same-day return e-fare for Saturdays, or a domestic leaving fri/return mon, or leaving sat, return tues. Either way, I see a Sunday having to be part of Ticket 1, to draw from your example.

Unless you find a way to nest two same-day return e-fares within each other - now that's timing!