What a fantastic application of Obsidian! I realize the this is making things more complicated for your friend, but there are two plugins that come to mind that might enrich the experience:
- Juggl allows you to show pictures as nodes in the graph
Juggl (Out now! 1.0.1): A completely interactive, stylable and expandable graph view plugin! - Journey: finds the line of connections between different notes.
New Plugin: Journey - Find the story between your notes
Another idea is to use this together, either in person or remotely, sharing your screen.
Please keep us updated!