If you have added new functionality to Zenoss that will break backwards compatibility, you need to provide code for your version that will allow users to upgrade without breakage.
Here's a breakdown of everything you will need to do in order to create your migration code and move your new code into production:
Create your code in the $ZENHOME/Products/ZenModel/migrate/migrate
package directory.
Add an import statement to __init__.py
Run zenmigrate --dont-commit iteratively to test