Questions about copying parameters

Rails
1

Hi,

What I am doing is:

         Category 1
             |
       ______|_________
      |                |
 Category 2        Category ?
  ____|____            |
 |         |        Topic ?

Topic 1 Topic 2

What I want to achieve is to copy Category 1(grandparent) and save as a
new record. When I copy Category 1, Category 2(parent), Topic 1 and
Topic 2 (children) will be copied as well.

Thanks.