I haven't explained any of this to the kids. I just don't think they would understand and I know if I ever had to tell them we were going to have pictures taken they would whine and say they didn't want to go. But I also know that once they're there they'll have a fun time. I also don't want to make a big deal out of it. I just want it to be a casual thing and not stress them out about it. For instance if they went for an audition I wouldn't want them to know it was an audition. I wouldn't want them to feel badly if they didn't get it.
I forgot to mention that it's for my little pony. Not sure if it's for a box or what though.