How does this work? I am asking because it seems to good to be true so asking if it is, and if so, how does it work? So if I buy this for my son, he can play on his 360 and then I get it for free so he can play it on the Xbox One as well? This seems to good to be true. You know what they say, if it's too good to be true then it is.

I bought him CoD ghosts for the 360 and then again for the Xbox One. So I would love it to be able to buy it once.

So if this is true, how do I do it?

*edit*

I found a site that says what to do, but me not being familiar with the web sites for CoD, I am not sure if it's legit or not. So is this a legit site?

http://www.callofduty.com/advancedwarfare/free-upgrade