Sort of, you can limit the list to specific root parent categories. What is meant by root parent is that the category is not a child of another category. This can be done by using the category shortcode option and a cMap enable shortcode option, enable_category_by_root_parent. Here is an example that will only show the root parent categories 2, 5, 12 and their children categories in the drop down.
[connections category='2,12,5' enable_category_by_root_parent=true]