My granddaughter sews in 4-H. I am her helper. I have to watch her. We both have Bernina's and she always wants me to bring all my attachments. I always have to take inventory of my feet or they migrate to her box. For birthdays and holidays, I let her choose her new foot.
You have to get them started early and make sure it is fun. I try to teach her the newest techniques (thanks Nancy Zieman). I haven't showed her my embroidery attachment. I know she will want to swap machines once she ever learns how to use it.