That is correct. In the past you could only upgrade by booking the highest level, but it seems lately they will allow you to book a lower level, but that level will be your max in your upgraded category. Which may be absolutely fine. Actually we often select a balcony that is forward or aft and I would love to be able to pay less and get the upfrade to a BB or BC even.
im sure you know this but at times the number of meals in the dining package may be less for an inside or OV than a balcony. When that happens you should receive the number in the category you paid for. However, we have often times gotten the Bal. Number, so if you do get the upgraded level, just quietly rejoice. Shhhhh.🤫