Multiple product categories in Slider/Carousel

I have created a slider, but I only have the option to select one category? How do I include more than one sibling category for the slider?

Hi,

This module is working like the other one, you can select only one category.
But what you can do is create a new category and add this category to the desired products.

The content of the module can be changed too dynamically by choosing the "synchronize" option.