Catch the event from Component Usage(reusing view)

Hello experts.

I ask your help.

I have a custom component usage(B) for a standard component(A). This B component have button "Edit". I want to make editable main component A when I click on button "Edit" (for subsequent storing data on "Save").

In other words, how can I catch the event of the B component usage in the main component A.

Maybe it's the events of controller interface or CALL METHOD iv_usage->subscribe_event...

Please tell me the steps to catch event from reusing view.