Ok so I want to buy my wife a new phone. Thing is, she's still on a family share plan with her mom, dad, sister and brother. I have my own share plan that I've been on and I want to get her a new phone without changing her number. I was looking online and they have the 5s for 49.99/two year agreement. I guess my question is: If I ordered that phone, granted they would send it with a sim for a new number. Could I take it to a store and have it switched to her (number). Would I still incur the price hit of the $40/month extra on my bill even though the phone isn't technically on my line? 
Edit: The obvious solution of adding her to my plan and keeping her number isn't really winning over.
Edit: The obvious solution of adding her to my plan and keeping her number isn't really winning over.