Create Issue Link Based on Selected Parent Issue

Stephen Higgins_i56eig

I am trying to leverage Scriptrunner to create an automation process that will link 2 issues together based on the selection made in one. I am not sure if this is as simple as creating a behaviour and if so what would I need to enter into the script.

Here is the process:

1. Originating issue has a field called "Client Project Category" that provides a list of active "Client Project Category" Issue Types within the same project the user is working in. 
2. The user can choose one of the active "Client Project Category" issues available. 
3. One they make the selection, I need the issue that is being created/updated to become linked to the "Client Project Category" issue chosen with a relation "Child of".