Divide large windows form in pieces

Question

I need to divide a large C# windows form in separate designer-files.

I added a class-diagram to indicate the complexity of my project.
The project consists of 1 main form (Green) and some smaller, less important forms (Blue).
The main form relies on several classes (Red) which provide Serial and SQL connections.

The problem:
The main form has 2422 controls which are constructed by the designer file. These controls are arranged in several tab pages which makes it possible to devide the form in different parts.
However, they still need to appear in one form.

What is the best way to accomplish this?

*It is impossible to use anything else than the Windows Forms designer

Answer 1

You can use UserControls and group the logical stand-alone parts there. And load them on request.