Data cleansing of a data management system involves merging two data objects by copying one or more attribute values associated with one a source object to a target data object and reassigning any instances that refer to the source object to the target object. The source object may be deleted. A user interface is developed that allows a user to select from a list of possible source objects and target objects, view attribute values for an object, view dependent relationships as dependency trees, indicate any attribute values that should be copied and any referring objects that should be reassigned to the target instance.