Trigger event of used component

I am trying to enhance a standard webdynpro component(MAIN COMPONENT), which uses another standard component( SUB COMPONENT ).

On Button Click action from MAIN COMPONENT I need to trigger event handler of button in SUB COMPONENT.

( as per requirement SUB COMPONENT button needs to disabled finally )

As part of the enhancement implementation, the system does not allow me to create interface methods/events in the SUB COMPONENT.

Please let me know, if any one has solution.

Thank you very much in advance..

Regards,

Damodar