Hello Ajeh,
Thank you for your prompt response.
The reason is the following:
The store will sell personalized booklets, where the cover of each booklet order can be customized. Customization is done by an external application i am writing, basically a mini cover design editor. This is because the attribut options entry methods are not sufficient to gather the graphcial information required.
The problem is that although within ZenCart each additional booklet order placed in the shopping cart appears the same, externally, each gets a different cover design assigned. To accomplish that I introduced a small change in the shipping_cart class, which adds a custom string into one predefined product attribute.
Unforunately, the add routine doesnt get called when zencart treats adding a product as a "change request" ... when a change routine in the shopping cart class is called, orders are already treated as combined.
thanks,
Daniel
p.s i guess i need to do more research to see where exactly zencart identifies that an add product request should be treated as changing an existing order in the shopping cart, and make attribute change already there.