If I ignore non-existent required elements, I won't be able to populate the case class.
The point of using data binding tool is to be true to the schema, so unless there's a really good compelling case, I don't see scalaxb supporting that. Do you have specific scenario that requires this?
If the real life data provided by the service does not conform to its advertised schema, then you you either contact the service provider or modify the schema manually.
-eugene