I just called the Disney help line, because I wasn't able to book FPs for BOG for my entire party at the same time. I was told that unless a person is invited, their FPs for BOG will be cancelled OR they will not be able to use the FP once they arrive. She said that Disney has a list of who they have invited and if you're not on the list, you won't be able to partake. YMMV, I'm only sharing what I was told.