wonder if they went to the premiere

yeah,it would seem so that they would have went.

You obviously didn't read The Last Battle. They (the Pevensies--not Pensevies--, their parents, and friends and relatives who had been to Narnia) were all killed in one catastrophic train crash in or around 1949 except Susan. Now, how did the books get written? Maybe Susan, who had renounced Narnia, underwent a profound religious conversion experience after her entire group of family and friends died, and caused the Narnia books to be written, and then films produced, of which she attended the premieres. Maybe, just sayin'. Even C. S. Lewis did not entirely give up on Susan, based on a letter he wrote a fan who asked about her, so I'm not giving up either.