I need to change our flights from July to October. Ryanair permit 2 changes for free. The original booking is for 4 people but DD1 won't be able to come with us in October. There's no way for me to indicate this while changing my flight. I can change 4 flights for 4 flights, but will there be an issue if only 3 of us turn up?

Also, anyone else finding the ryanair 'free' flight change typical Ryanair taking the p*? When I look up the flights in a fresh browser the flights are cheaper than the prices I am offered in the change flight section when I go into my booking.