Delphi 2007 and C#.NET integration

We have an Application developed in Delphi, with a Tree Structure Note similar to the attached screenshots and Tabs being displayed on the right hand side. The current application is developed in Delphi. We have another application developed in .Net with exactly the similar structure, Tree Node on the left hand side and the Tabs on the right hand side. What we need is a.) The Tree Structure though is built in Delphi is able to refer to the .Net forms and display the .net Tabs alongside the Delphi Tabs. b.) We want them to be seamlessly integrated. So basically we have a common tree structure and still able to display the .Net Tabs and Delphi Tabs next to each other. It can be Delphi form as the parent form or .Net Tab as the parent tab Deliverable will be a.) Delphi Code b.) .Net Code Sample project and procedure how this has been achieved. The best methods as how this can be achieved.