I mark each ornament with their name or initial and the year it was received.
I also do one for James and I. Because I love ornaments. And this is how I control the after Christmas clearance decor shopping that I would do if I didn't already pay full price for 5 new ornaments. I'm already up to a gazillion boxes of Christmas decor.
Then when the holidays are over all the ornaments are removed from the tree and separated into their own boxes. Each of the kids has a little box with their name on it. This way each year they can put THEIR ornament on the tree. And one day should they move out of our house they will have ornaments for their first Christmas tree.
Yes, it's probably one of my better ideas!