Construction of multiple model forms and controllers

I have a problem with the construction of a sequence of input forms. The model being created and edited is called a Portfolio. The portfolio contains multiple subordinate objects, such as Stock, AssetClasses, Sectors, and worker objects link StockPosition, SectorPosition, and AssetClassPosition. I have the belongs_to and has_many relationships working and have written scripts which demonstrate that once constructed, the associations work.

My customer wants the Portfolio object to be created across 3 distinct pages, call them P1, P2, and P3. I cannot seem to set up a controller and action methods which will allow me to create the Portfolio base object in a new/create pair of actions, and then allow multiple edits on the object, call them P1_edit/P1_update, P2_edit/P2_update, P3_edit, P3_update. I am also lost on how the routes should be configured to do this sort of thing.

Most things I have done with Rails up to this point were based on the RESTful style, which only allows for a single edit/update action pair on any given object. So, how does one construct a controller/routes/ views set that will support a sequential creation and configuration of a given object?

I have been at this for 3 days now and my hair is getting whiter. I would appreciate some sound advice.

Thanks in advance for your help.