I need to transform GML to other regarding to new XSD schema. I've got following problem, pointed during oldGML validation by new XSD schema:

• Element <gmd:CI_ResponsibleParty> is not allowed under element
  <przedstawiciel>
• Element <zrodlo> is not allowed at this
  location under element <GES_BudowlaPodziemna>
• Further elements required
  under element <wladajacy>
• Value 'BrakInformacji' is not allowed for element
  <bt:lokalnyId>
• Value 'zasuwa' is not allowed for element
  <rodzajUrzadz>.

Some of them looks simple ("Value ...is not allowed") but changes of schema elements relations seems to bring some difficulties. What is the best practice to handle such GML tranformation? Attribute mapping using XMLTemplater? Constructing XSLT file or something else?