Help Needed! To anyone who is good with music mixing

[fantaisie.sign]

I'm still looking for music in case I do perform in another talent show this year. One of the songs I'm interested in is I WILL by Namie Amuro. I downloaded the instrumental version of the song and I was pleased with it, except that the background vocals are completely missing. There are 2 versions of the song with the background vocals in it -- the original I WILL and I WILL (in LA), but Namie is singing along.

Is there any way that the background vocals can be added to the instrumental? If so, will anyone be willing to do this for me and make a file for it just in case I can't find anyone else to?