Paid Upgrade AF/Delta
I'm flying MSP-CDG in early July on AF metal but booked through Delta. Usually there is an option online to pay to upgrade to Comfort+, etc after booking a ticket on Delta. I haven't been able to find that option by logging into Delta using my Confirmation # or by logging into Air France using my AF Confirmation number. Any suggestions for how to do this or is it not an option on Air France? The plane looks wide open so it seems like they'd like to make extra revenue through upgrades like this.
Side note: Has anyone flown this route? I'd like to read about your experience.