Add custom field in powl Planner Monitor SAP GRC

Hi experts,

I nedd to add a custom field in result list of POWL Planner Monitor.

In method IF_POWL_FEEDER~GET_FIELD_CATALOG, the coderefersto the structure GRFN_S_UI_PLAN_MONITOR.

Thesystem does not allowyou to enter a custom append in structure GRFN_S_UI_PLAN_MONITOR.

What's the way to insert a custom field in this powl standard ( CL_GRFN_POWL_EVA_MONITOR ) ?

Thanks.

Andrea.