question about MVC pattern

Hi,
I am trying to implement MVC pattern in C#.

My application is an extensible application composed from add ins\plug ins
hosted in a HOST application.
on the left pane there is a tree which list the add in,and on the right pane
there is the addin's view

The add-in can inject menu and buttons into the HOST application
and can response to user input.

as far as I understand the controller is responsible for handling user
input/
my questions are:

1.Is it ok to replace the controller for each plug in?
2.what if some input is handle by the host application
and some in the plug-in,is it ok to chain controllers in MVC pattern?

Thanks.