Limit articles in instances

Hello,

Is there a way (in PRO version) that the accumulative category limit is set in instances?

For example, I have set that one category has min order limit 20. The users cannot purchase 19 articles in this category, but they can purchase 21. I would like that they can purchase only 20, 40, 60, 80, 100, 120… articles.

If that’s possible in PRO version I would gladly purchase it.

Thanks in advance.