Where should I select a SWISS-booked seat when Edelweiss operates the flight?

What this answer depends on

• SWISS published advance-seat selection and Edelweiss operating-carrier handoff; European fare examples only where explicitly stated
• A SWISS booking reference and an Edelweiss-operated flight can coexist. The airline’s seating page expressly sends that flight’s reservation to Edelweiss. Use the operator’s current rules and actual quote rather than repeatedly trying to force the SWISS seat flow to represent another carrier’s entitlement.
• SWISS’s European Flex and Comfort examples differ in when selection is included. A benefit at check-in is not a promise that the same choice can be reserved free earlier. Confirm the fare and timing of the intended action before treating a displayed advance charge as an error.
• SWISS’s current page describes fare- and category-dependent changes, including a selection-fee waiver for some same-or-lower-category changes. That wording alone should not be turned into a guarantee of no possible price difference. Read the actual final quote and keep the original category confirmation.
• SWISS directs passengers on Edelweiss-operated flights to Edelweiss’s website for seat reservations.
• SWISS describes European Flex advance Classic selection and Comfort selection at check-in as different included entitlements.
• SWISS seat changes depend on fare and category, with a fee-waiver provision for some same-or-lower-category changes.