Help ML

[KX300]

Hello,
Can someone help me explain how I can proceed as I am stuck.

My company will sell in ML in different variants with a product that has a fixed ML (about 100 ML) we want to change first and foremost so that the products will be in ML and not piece

Then we want to put some kind of purchase stop (at about 15 ML) then it should not be possible to order from that product and it should say sold out. I have not found anything on youtube that can help me with this and am going to take a chance here if anyone knows.

Thanks in advance