Not able to populate Associated Ticket number in Email BO

Hi ,

Our requirement is to create a record in "Interaction" section under Service -> Ticket when we send an email through custom code.
1. I am not able to find the BO being binded to Interaction in order to create instance for it.
2. In Email BO, "associated ticket" number is binded to Activity -> InitiatingActivity -> BusinessTransactionDocumentReference -> ServiceID -> ID -> Content.
But, in repository, this "InitialtingActivity" node is not visible. Kindly guide me on how I can populate this field.
My assumption is : If we can associate ticket number in the instance of Email , its record will automatically will be reflected in the Interaction section of that particular Ticket.

PFA word document for detail description.

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