My children now have one cup.
I got rid of all the glasses in the kitchen when they were at school one day and gave them each one cup.
They got to pick which one was theirs of course.
They are to wash it, keep track of it, and that is their only cup.
To this day they still have the cups and they care for them.
It really worked for me.
I used to have the counter and sink full of cups but not anymore 😉
Momentary Lapse Of Sanity 