[jaszman]

Fish, your lucky that your plan provider is Tmobile, one of the best customer service groups out there.

First, get straight what it is that you want to do, (get a BB and a BB data plan, replace your current phone data plan with a BB data plan, etc)

Then just call a Tmobile rep with your proposed changes and ask what will be the least expensive way to do that. Be sure to keep clear notes of what you are told, and be aware of any trade offs that will be made to accomplish that. You won't be able to make changes to the plan because it is your parents that are the primary on it, but you will be able to go to them with the answers to the questions they will have about your proposed changes.

When I first went to Tmobile to add smartphones and data to my plan (for my daughter), I was shown how eliminate waste in my plan to pay for my changes at no additional cost to me.

Good luck