It is so much more cost effective to have your family on a Share Everything plan! I will be delighted to clear this up and I apologize for any confusion.
I think it may be in the way the question is presented so I want to cover all bases.
Scenario 1: Your sister retains her Verizon Wireless phone number and her current Verizon Wireless phone and we process an Assumption of Liability(AOL) into your name.
Answer: The Early Termination Fee(ETF) does not apply as nothing is being terminated. You are now assuming the responsibility of the phone number and the ETF. If you cancelled/disconnected the number later you would be bound to the contract terms.
Scenario 2: You add a new line of service to your account for your sister to use and cancel the other account.
Answer: Yes the ETF would apply and I wouldn't recommend this.
Scenario 3: Your sister isn't currently a Verizon Wireless customer.
Answer: I'm not sure, it depends on if she's still in contract with her current provider, but she can check to see if she can port her number here http://bit.ly/qDhvBY
I have to assume this is probably revolving around scenario 1 which means you will be just fine. She has to give us permission first for you to take over her number, but that's easy!