Modifying an XML Schema Collection
To add schema components to an existing XML schema collection, you can use the ALTER XML SCHEMA COLLECTION statement. For more information, see ALTER XML SCHEMA COLLECTION (Transact-SQL).
See Also
Reference
Managing XML Schema Collections on the Server
Guidelines and Limitations in Using XML Schema Collections on the Server
Permissions on an XML Schema Collection
Concepts
xml Data Type
Typed vs. Untyped XML