Upgrading & Transferring to Keep Unlim Data Using Amazon, Walmart, Best Buy...

[npro1464]

I have a question regarding upgrading at vendors like Best Buy, Walmart and Amazon. I wanted to use my brothers line (a dumb phone) to upgrade so I can keep my unlimited data but I wanted to take advantage of the black friday deals that are going on. I know Amazon expects the upgraded phone to be active on that line for at least a month. Does anyone know if thats the case with Best Buy or Walmart? I'd really like to take advantage of the Walmart ($129 + $100 gift card) or Sams Club ($.97) deals for the Galaxy S3. Thanks!!!