Originally Posted by
ijgordon
That's not exactly correct. Despite the wording on CO.com that only codeshares earn EQM/Ps, it has been well-documented here on FT that you will earn full EQM/Ps as long as the VS flight you are on is also sold as a CO codeshare. You don't actually have to purchase the CO ticket, you can buy from VS with a VS flight number and will be OK.
That's what
NYC_747 said. The flight can be booked anywhere and under either the VS or CO code. The key is that the CO code exists on it, even if booked elsewhere.