Primary Ticket field on Universal Request

Hello,

I am working on universal request application and want to know few things. When the primary ticket(incident) is been transferred to different department the primary ticket field on Universal request will get cleared and few work notes are been added to incident and UR. Can someone please let me know where was the code to clear the primary ticket and code for adding notes I want to make few changes to the code.

Thanks,

Prudhvi