How about giving this to me?

"Hey, Isabella. Even though you quit cosplaying without a word, saying you didn't want to be a cosplayer anymore, I don't know why. Maybe it's because you're busy with school? Or maybe your life has changed recently? We don't really know. But we will always remember the days we boldly presented ourselves together.

"Ah, I'm not good at saying these kinds of things, leaving messages of blessings for others. I haven't learned how to do it over the years... But what I really want to say is, I've always seen you as a very good and kind sister. No matter where you are, no matter if you continue to cosplay in the future, we will always remember you and how you helped us complete that convention.

I wish you all the best, and may you succeed in whatever you try. Good luck!"