I'm on a family plan with someone who actually has the tethering plan with Verizon. (I do not) If I use their phone number for the user name to login on my tablet instead of mine. (their#@vzw3g.com instead of my#@vzw3g.com)

Can I get internet without a huge $1.99/MB charge on my bill? (Internet with no additional charges from what we have now)

Would I also need to use their number when I do the dun hack on my phone, or would it work with my number? Would both phones be able to use it at the same time or only one? And yes I have the permission of the owner of the other phone to do this.

Has this ever been tried?