I have a credit on CO that I want to spend on DL-operated flights. How can I determine by myself if (for example) DL #147 from EWR-ATL is a code-share with CO? If I learn that it is indeed a code-share, how can I determine the CO price?

(FWIW: I'm trying to fly EWR-ATL-TPA & TPA-ATL-EWR on DL, but want to use my CO credit to pay for it, so I need CO flight numbers.)