I’d suggest reading some of the learning paths that can be found here: https://gettingstarted.mendixcloud.com/link/path
They are really good and will explain how to do this.
The short answer:
Your domain model is looking good. If you want to create new controlling objects for an existing project you can add a button to your project_newedit page that triggers a microflow in which a controlling object is created and associated with the project.
This is my microflow that will be triggered:
And this is the overview page
But with this microflow the Controlling datas will be added on every project