Suggest linking of content types
You should take a look at References for the linking part, and also Workbench for the moderation part, and lastly Field Permissions to give users access to do the linking.


Create a Node reference field on one content type, to link the child node to the parent (or vice-versa)
Use Field Permissions to grant everyone access to enter/edit the field
Use Workbench to force changes into a new revision which need to be approved.