If the name and address don't match the original invoice when you register the GPU it will be considered a second hand product. It will still have a warranty but will be exempt from being able to use "step up" and will not be able to purchase an extended warranty for it. 
 
I'd just have your family member register the card on their account so the invoice matches up and you have all the benefits intact. Doesn't matter who is in "possession" of the card, just that the original purchaser be the one the warranty, RMA or step up be initiated through. If you are fine with losing than, then there is nothing wrong with registering it yourself as it will still be covered under warranty regardless. 

good to know!