For data sets created using a file upload or from the Data Source Library, you can add records.
You cannot add records to a data set while an enrichment on that data set is running.
When you add records, Studio does not allow you to make any changes to the attribute configuration. It takes the selected data and adds it as new records to the existing data.
Note that Studio does not check whether a record is a duplicate of an existing record, so it is possible to add duplicate records to the data set.
From the Data Sets page, to add records to a data set: