In VTiger 7 you create Custom Modules. The purpose of this extension is to help the user to create a module according to his requirements and you can relate modules with each others by using this extension.
How To Create Custom Module
Go to the “CRM Settings” and click on the “Other Settings” drop down menu button and select “VTE Custom Module Builder“
From here click on the “Custom Module” button to create a new module.
Set the Module name and label and click on the “Save” button to create the module.