You need to configure the parameter required for controlling the Master Data Management feature for specific dimensions.
Employee
User
Business Location (Employee)
Internal Organization (Department and Organization)
Job
HR Assignment
HR Person
HR Person Legislation
HR Position
Turn on the feature for a given dimension forever (never turn off).
Turn off the feature for a given dimension forever (never turn on, so no impact at all).
First turn off the feature, and then turn it on from a future incremental load.
Other implementation scenarios (such as turning on first and then turning off the feature, or switching between on and off of the feature) are not supported by regular incremental load. They would require full load of the impacted dimension.
To enable the Master Data Management feature for a given dimension, you need to set CROSS_REFERENCE_ENABLED to Y for that dimension using the Configure Data Load Parameter for Master Data Management task in FSM.