It's difficult finding discussions on this specific issue because the terms are prevalent on so many topics that only address simple 1-Parent-to-1-Child relationships. I want to create a node that is the Child node of two separate Content Types, both of which are Child nodes of separate Parents of two other Content Types.
Maybe a solution is to enhance the Node Reference field type to pass the nid of the selected node to another Node Reference field that can use that as an argument for a view to populate its list? Instead of specifying the actual Argument, specify the field where it's coming from.
Since I had a free day available I decided to take a look at the first alpha release for Drupal 7. I didn't plan on doing anything fancy like upgrading one of my existing sites, I just wanted to explore the features that come with a new site. The experience proved to be a bit disappointing, hence this post.