Thank you for your questions!
In Store Manager you can find feature to reassign subcategories, though, unfortunately, it is impossible to copy one subcategories for few parent categories, it can be assigned to only one.
You can manage category tree, changing categories position by setting appropriate sort order for each category, please, check screenshot: http://screencast.com/t/gqGqcO5ODqAny
of categories won't deleted.
Please, let us know if any other assistance is needed. Have a great day!