OK well you need yo figure out how important it is to him that his parents are there, and why does this Aunt K person hold so much importance on whether or not they go. Then decide if it's work moving your date....would they be ok with October or December or are there specific times in November. Then again I would say reserve the date you want this is your wedding and you can do whatever you want. My father has not been on board for my wedding since we announced it to be in Mexico, however I had a feeling he would turn around so I continued to plan what I wanted. As time goes on people that are really close to you will start to lose the attitude, at least that is what I've found. We've been engaged for over a year, and with 9 months until our wedding my dad finally admitted the real reason to me and it's not because he doesn't want to be at my wedding, so now he'll be there. I think if you stick your ground they will come around. If you don't think so and it's extremely important for them to be there, then a compromise may be a good idea.