Expanding category depth on 'New Products' displayed

I'm trying to find a switch that enables me to include products from embedded categories in the 'New Products' module below index listings.

Took me some time to realize that the products shown in the 'New Products' module beneath a category listing only display new products placed in the subcategory directly below the listed category. Products within second level subcategories are not displayed.

To illustrate; I've set up a category with two subcategories, in one of them I've made two other subcategories (with products of course ;-).

Top>Category1>Subcategory1>Products
Top>Category1>Subcategory2>Subcategory3>Products
Top>Category1>Subcategory2>Subcategory4>Products

When listing Category1 with the 'New Products' module enabled only the new products in Subcategory1 are displayed. Products in Subcategories 3 and 4 are omitted.
I expected to find a switch with the 'Admin/Config/Max values' to alter this behavior to extending the selection to embedded categories (change 1 into 2) but have not found it.

Is it possible to adjust this somewhere in the database or code to include products lower in the hierarchie?

Using ZC1.3.6 by the way. Should have mentioned that.

There is not a switch for that ... currently that is the way it is setup ...

You would need to recode for this to manage the categories and products at deeper levels ...

Would this be very difficult and require highly developed PHP skills? Where do I start with this?

I coded it once before ... but I would have to recode it to rember the changes ...

You would need to look for where the code is pulling the products based on the current categories_id ...

Would it be possible to 'borrow' the code from the index ('home page') listing? It's here where the 'New Products' module selects products from all categories. Isn't this the place to start?