Good to know. So not everyone gets to participate. You have to be chosen, correct?
Yes, but it's a good time to do it because you're going with just your party, so you're guaranteed for someone to do it. My advice is not to you-tube it so you'll be surprised by the special effects. It's really fun and cool, but basically the same thing each time, so it's best done without spoilers.
When we went, my ODS was incredibly HP obsessed and was dying to do it. YDS was interested, but not a super-fan. We went 6 times over two days between Hogsmeade and Diagon Alley, and kept not getting picked. ODS even wore his custom quidditch robe (Halloween costume where he was not Harry, but himself as an exchange student from Ilvermorny playing on the Gryffindor team - because he's read all the books and Pottermore stuff so he knows that as an American he wouldn't go to Hogwarts). Still didn't get picked. I started to think it was because they look the same age, and no one wanted to pick one "twin" over the other, so they just never got chosen. When we were waiting in line for the 7th time, one of my kids burst out, "we keep doing this and no one picks us because they think we're twins, and we're NOT!" Before we went in, the handler conferred a bit with another performer. We were sure he'd get picked this time, plus there was only one other kid, so the odds were good. Nope, other kid got picked. My son was trying so hard not to cry and ruin the other kid's experience, but he was so disappointed. Then as we were leaving, one of the assistants called us back, and said, "these are the two you were asking about, Wandmaster." They did a special two-person ceremony for them both. It was incredible! People talk about pixie dust at Disney, but this experience was just magical, and so well done, especially after the repeated disappointments. It was also great that after seeing the ceremony so many times, this sibling double ceremony had a twist that made it fresh.
Are the wands that choose their owner in the ceremony also interactive? Or are those different wands?
Yes, they are interactive.