here is our requirement:
we need limit the each order can only purchased 8 milk powder products(not for single products, but for different milk powder products), how can we do?
for example:
customers choose milk powder A + milk powder B or any other milk powder product, the total quantity in shopping cart can not greater than 8. if it's greater than 8, it can not checkout and show reminder" the maximum quantity for all combined milk power products is 8".
btw: we are using version 3.7