When a graph source is used, you can clear the InternalItems and InternaLinks collections before loading the XML file. This logic can be triggered by a custom command implemented in your ViewModel. Furthermore, you will be able to trigger that command from code behind just before loading the new XML.
Regarding the requirement for custom serialization, you need to have in mind that the RadDiagram uses SerializationService to manage those features. You can create your custom service and use it instead of the default ones. For more information please refer to our documentation
I hope this information is helpful.
Pavel R. Pavlov
TRY TELERIK'S NEWEST PRODUCT - EQATEC APPLICATION ANALYTICS for WPF.
Learn what features your users use (or don't use) in your application. Know your audience. Target it better. Develop wisely.
Sign up for Free application insights >>