1. A method for creating an add-on application, comprising: creating, with an electronic processor and in an electronic storage medium, a business add-in definition object within an add-on application development environment, wherein the add-on application is based on a foundation application, wherein the add-on application comprises software code, and wherein the add-on application requires at least one function that requires at least one code modification within a modified object of the foundation application; defining, with the electronic processor, a method in the business add-in definition object for the at least one code modification to provide the at least one function, wherein the add-in definition object enables the at least one code modification to be switchable between an activated and deactivated state; inserting a call to the add-in definition object in the modified object; responsive to completing development of the add-on application when all places where modification of the foundation application are known, copying the add-in definition object that enables the at least one code modification to be switchable into the foundation application; and responsive to a new version of the foundation application being created, copying the add-in definition object into the new version.