In order to manage XML documents, native XML databases use specific encodings that map the hierarchical structure of a document to a flat representation. Several encodings have been proposed that differ in terms of their support for certain query workloads. While some encodings are optimized for query processing, others focus on data manipulation. For example, the Pre/Dist/Size XML encoding has been designed to support queries over all XPath axes efficiently, but processing atomic updates in XML documents can be costly. In this paper, we present a technique, so-called structural bulk updates, that works in concert with the XQuery Update Facility to support efficient updates on the Pre/Dist/Size encoding. We demonstrate the benefits of our technique in a detailed performance evaluation based on the XMark benchmark.