Add a custom column to the UDF from custom MDF

[SORON1]

Hello experts,
I would like to add a custom column to the UDF, but it is not mapped to the HRIS Field of the Data Model. I want to add a custom column coming from a custom MDF, how would I have to do the mapping? Is it possible that the field of a Custom MDF of a Custom Porlet is mapped to the UDF so that it is visible in the User Directory File?

Thanks.

Kind regards.