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You as a traveler can’t just select which airline you want to use your cheapoair issued EVA ticket on; the ticket would have to be endorsed over to the new airline by, possibly, EVA if they retain control of it, or cheapoair if the ticket has now been dropped or canceled.

If you originally purchased the ticket that was actually issued from cheapoair, they are your travel agent of record and it’s likely they will need to sort it for you (though when the original flight was canceled and you were then denied boarding due to oversales by EVA, they should have arranged alternate flights for you on the spot, as they had control of the ticket).