Unwanted child Table update

I do not know in what way you purchase things that are not created as an item in the system. I got the advice to make a Dummy item and change Item Name and description in the Material request.
This is not nice, but it should work. The big issue I have is, that if I change the item name and item description in the Item table, and then change the quantity, then the saved item description and name is reloaded from the db. This is very troublesome and will not be accepted by the employees.

In this case if I change the item name to “Laptop for …” and change the quantity from 1 to 2 than it goes back th the description and name “test”. If I change first the quantity and later the name, it’s fine and works. But everybody first writes the name and then the quantity
How can I change this behavior.