I actually chatted with an NCL rep today about exactly that. (I'm a first time NCL cruiser this year, too.) She confirmed that my assigned cruise planner had linked our two cabins, but there is/will be no way for me to see that. (I wish there was some way that this was visible to the customer, but oh well.) I can making dining reservations for everyone when the booking window opens, but that is it.
I am guessing you are also the travel planner for your family? I wasn't concerned about groupings on the excursions, but I found it annoying and inefficient that I cannot just book everything for the whole family and be done with it. I had to sit there side by side with my husband and walk him through each thing he needed to book (excursions, airport transport, etc.), one at a time. The site is terrible and laggy, which I guess I've gotten used to while researching the port excursions, restaurants, etc., and then the charges wouldn't go through for him without multiple efforts. Not the end of the world, but definitely not user-friendly for families with multiple cabins.