listener from two fields in linked ticket updates a field option in current ticket

[Scott Federman]

I have two projects.

AI has two different date fields. 

• Data Discovery Date (Modex)
• Data Discovery Date (Pilot)

DI has two different fields

• Data Discovery Complete Date
• Data Discovery Comlete
  • Yes
  • Null

When one of these fields are filled out in the "AI" ticket I need the Data Discovery Complete Date copied over to the Data Discovery Date field in the linked "DI" ticket and the Data Discovery Complete field needs to be update to "Yes" 

Can someoneshare with me how i would create a listener for this action to occur?