Is it possible to run a web application written in ASP.NET Framework 4.0 (Sub-Folder) under a web application written in Framework 2.0 ( Root)?

I am having trouble doing it. Getting error becuase two different web.config file in each one of them.

In my ROOT folder I have a web application written in ASP.NET framework 2.0 . Now, I have all kind of sub-folders for other applications in .NET 2.0 or 3.5 . This is the first time I have sub-folder with application in .NET 4.0.

There is a conflict between two web configuration files.
How can I solve it?

NOTE: I can not change the Root or other sub-folder, only If there isn’t any other way to solve this.