This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Define a new typed complexType , let's say 'full_name', which includes'first_name' and last_name and add the element 'full_name' to the Request type/element along with 'ssn' but now use 'xsd:choice' instead of 'xsd:sequence'. This will allow either 'full_name' or 'ssn'. But this will add one new element 'full_name' to encapsulate 'first_name' and 'last_name'.