What functionality is missing? What is unsatisfying with the current situation?

In the current version of organisational charts, any given item can only have one parent, as such if I was making a spell system for my world using this system where someone has to learn specific spells before they can learn other spells, I can’t have so that they need to learn two spells before they can learn the current spell.  

How does this feature request address the current situation?

Multiple parent items allows for people to directly link spells together.  

What are other uses for this feature request?

Multiple Parent items expand the organization chart to allow all systems which require multiple parent items and/or multiple child items, such as technology trees, crafting trees, cause and effect trees, more complicated command trees where division of power exists, etc.