Loading the Tree in segments

I am working with an Elixir Org Chart.  The problem we have is that the amount of data we return is so massive that we want to load the tree in segments.  How do I time it so that I call my web service and load more of the tree each time the web service returns?  Do I setup some kind of recursive call to the webservice so that in Flex each time I get a response I call the webservice for more information and load that when it returns then call the webservice again?  I would assume with this scenario that I have a listener that will listen for each return of the web service and then in the WebService_ResultListener I would create an IHierarchicalView orgView  = chart.dataProvider as IHierarchicalView then attach those to the end?  orgView.addChild(xyz_Result);