Gravity form prioritizer

Hello EveryOne, We have a list of 60 flashcards and we want our clients to:
1- choose 20 out of 60 in the first step;
2- choose 3 out of 20 selected flash cards in last step.
Is it possible to do it by GravityForms?

using GP limit checkboxes, I can limit the first 20 checkbox (Flash Cards), but I don’t know how to take selected checkboxes into second page (so 3 of them will be selected).