How to copy Location Country field value from Parent object to Child object field default value? I use Parent and Child content types with a Field used in both types.

I would like Drupal to automatically propagate the Field value from Parent value to the Child field default value.

How to do this ?
I am interested specificaly in an example for Location>Country field.

I use node reference or organic groups modules to set up Parent&lt;->Child relationships.
Guess you want this to take place, when you create (aka save to db) a new node. You could do this in hook_node_presave.