We have 1 minor and added the HIA package after initial booking. Got it with tour credit, dinner credit and internet package for her. Got a discount for not having alcohol but soft drinks water etc I think. Booked with HAL directly and had to call in twice to get an agent who understand that we needed a discount since the minor can't use the alcholic drink option.
Your teenager sure will need their own internet package or have to use one of yours, blocking you.