Extending Fiori MyInbox -(Multi-Select) Task Summary screen with addition columns.

Hi SAP Fiori experts,

We have implemented Fiori MyInbox app for approving Purchase Order release. It is working fine with standard functionalities but our client wants to see extra custom columns on "Task Summary" screen while approving using the Mult-Select functionality. The standard screen shows only Task Title, Created By and Due Date columns.

Can anyone give me a hint to how to enhance the MyInbox app?

System Inform:

Architecture model: Hub Model.

GW system: NW 7.4

Backend ECC: NW (7.4 ) EHP7

Your feedbacks are much appreciated.