I like the second idea and will explore it, thank you! Perhaps I could take all info of the product being added to the cart by the user, and create a similar one on the fly with different props instead.
The first idea was somehow tempting but too risky, as you said the same product can be (hopefully) purchased by several customers at the same time. This is why I wanted to edit the items in the cart instead, which are instances of the product and not the “blueprint” itself.
Thanks again much appreciated 
