is an embedded multiple node creation form possible?

Hello,
I have a Drupal 6 site that allows users to create nodes using the Nodereferrer_Create module. Basically, a link to a certain path, something like /create_referrer/0/node/0 is placed on a node. When the user clicks this link called "Add" it takes them to a node creation form with one field already filled in, pointing back to the "parent node" which was the node they were on when they clicked this button/link. This works fine.
My problem is that, since all content on my site is moderated, there's no easy way for people to add multiple nodes, child nodes, grandchild nodes quickly and easily. They can add a node, wait for it to be moderated and approved, add a child, wait for that, then add a grandchild. Or, they can go to "My Nodes" and see their moderated nodes and add the children and grandchildren. This is too much work for an impatient user.
What I want to do is somehow let the user fill out one form that would actually be creating three nodes at once. It would be like saying "I want to add node for year 2010, then node for Ford (one make from year 2010), I want to then add Focus (a type of Ford)." but to do it all with one form that might look like:

Year:

Make:

Model:

and perhaps Make and Model could be optional. If content is present in the fields, child/grandchild nodes are created, if not then just a Year node is created.

These can't all be part of the same node, because each has its own additional details which require that they be separate.

Is there any solution to this that I can implement and keep Nodereferrer/Nodereferrer_Create modules? If not, is there a solution without those modules?

Thanks !
+Bill