The best practice for deterministic hiding would be:
- Create a new Category (any data in this category will be hidden by default), inside we will recreate the Date of birth field.
- Employees that do not want their data public will need to have the data removed from the original Date of birth field
- We will populate the removed in the newly created category.
The best Practice for hiding ALL the Birthday data would be:
- Go to the permission group All people — others’ data.
- People's data->People->Basic info,
- Restrict visibility over it.

