Multilevel Categorization in the normal Appointment View

Dear experts,

We're using CRM 7.0 SP3.

We're well aware that Multilevel Categorization as per Standard is supported in IC Webclient in Interaction Record View and not in the normal Appointment View (i.e. UI Component BT126H_CALL).

However we want to use Multilevel Categorization explicitly not with the Interaction Record but with the follow-up Appointments.

How do we implement this requirement?

We already enhanced the Component BT126H_CALL with a Custom-Controller ZBT126H_CALL/CUBTCategoriesCuCo and adjusted the Runtime Repository taking the Component BT116H_SRVO as an example. But we fail while trying to add BLOCK CategoryDDLB to our Configuration of the View BT126H_CALL/SCDetails - nothing in fact gets added.

We would highly appreciate any hints how to get our work finished.

Many thanks in advance! Kind regards,

Sasha