The Embed Xml data processor allows you to embed harvested xml as part of your export file. While this gives you a very flexible way of embedding harvested Xml, there is of course also a risk of embedding corrupt xml. Make sure that the harvested xml is valid. The data processor attempts to validate the harvested xml, and will throw an exception if invalid xml is detected.
If you embed using mode DocumentInner, see below, make sure that the embedded nodes do not rely on namespaces defined at the root node of the harvested xml document. If such a dependency exist, you must manually define these namespaces in the marshal tree, probably in the namespace manager of the parent query node or the root node.
Since Marshal does not have any knowledge of the xml that is embedded at runtime, you will not be able to generate a complete Xsd for your model using Marshal. If you need an Xsd, you may generate an Xsd and complete it with a definition of the embedded nodes.