Thanx for your immediate reply, Gavin! We really appreciate the work you devote to Seam :) I really tried to work this out, but could not manage. Here is what I did: 1. @DataModel for the list of sub-entities. 2. In the get method for the sub entities in the action listener (which is returning the list outjected with @DataModel), I fill the list of existing sub-entities with empty ones as required (see bottom of post for explanation) 3. One sub-entity per factory is displayed (also if it did not exist yet) 4. I enter something into the input field (JSF inputText tag in data table) Until now, everything worked. 5. I execute the update method. Whatever I input as a value for the sub-entity is not saved to the DB. A log output shows that the actionlistener update method receives a main entity object with an empty (size = 0) list of sub-entities for the update. Do I have to manually link the @DataModel list to the main entity? I did not think so... Your help is greatly appreciated. Any hints? I am happy to supply source code snipplets if required, just did not want to crowd the post with it yet. @2: The data structure is: parameter > settings of the parameter > factories (a parameter has settings, one for each factory where it exists). The number of factories is constant. A parameter may not have a setting in a factory yet. We would like to edit/update the parameter settings together with the other parameter attributes using a single screen. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4015491#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...