I've tried to add a new file property in share form, but i can't make it appears. I've created a new aspect with the new property in \tomcat\webapps\alfresco\WEB-INF\classes\alfresco\model\contentModel.xml, but it doesn't works. Later, i've added the new property in a existent aspect and the new property doens't appear too.
The property that i want to add is a list where the user select the type of the document.
If you don't have any error in your log, the data have actually been added. You just need to change some bits in web-client-config-custom.xml (in the same extension repository) to make those new properties appear in the UI.