George Flanigen told USA Today McBride was filmed against a green screen and digitally inserted into Presley's famous 1968 "comeback" TV special, in which he sings the holiday classic.
"There's a spot between (guitarist) Scotty Moore and Elvis that's open, like somebody should have been sitting there," Flanigen told the newspaper. "We're like, 'We could probably figure a way to put her with Elvis.' We scoured the footage and picked shots of Elvis throughout the whole special to be able to put them together. There are shots where he and Martina share the frame, where he looks over at her, where she looks back at him and sings and smiles."
The song will be featured on the new album "Elvis Presley Christmas Duets," in which Presley sings with the likes of Carrie Underwood, Amy Grant and Olivia Newton-John, USA Today said.