Customized ConfigurationSection in Derived Project

I created a base library where my customized configurat开发者_如何学Goion section is located. This works fine so far - also in derived libraries:

<MySection>
    <Tooling>
       <add Key="asdf" Value="bla/>
    </Tooling>
</MySection>

Now i want to modify the configuration section "MySection" in a new derived library with some properties. but i always get an exception that the section 'SpecialTooling' is not known - because it is defined in the derived class.

Is this possible todo?