How to extend controllers of a Rails 3 Engine in the main app?

Rails
1

Hello,
In my Rails 3 app I use an engine having PostsController. I would like
to
extend it in the main app by adding and altering some methods. I have
tried
some things which you can see in Extending controllers of a Rails 3 Engine in the main app - Stack Overflow .
There I am facing an exception since PostsController has different
superclasses in my engine and main app. Do you know how I can fix it? Is
it
possible to fix without modifying the engine?

Thanks