Permissions from SAP CRM on premise to SAP Marketing Cloud

Hello SAP Community,

we want to synchronize marketing permissions from CRM on premise to SAP Marketing cloud.

I already found the following blog:

Blog Marketing Permission

and an added Guide:

Guide Documentation

Why do I need to create a Z-BADI in the CRM? Is this Z-Badi really necessary?

What we have is the Basistype: CRMXIF_PARTNER_REL_SAVE_M03

Furthermore I have in the CPI the standard iFlow:

1)

2)

3)

In this standard iFlow I have the mapping to the marketing perimissions between CRM and yMKT.

Is it now possible to add the "Replicate Contact Permission From CRM to yMKT" Mapping into our Partner_Rel Mapping?

Does anyone of you have experience with this iFlows and may give me a hint?

BR Christof