Add Data to a Previously Launched Assessment

It's possible to add data to a previously launched assessment; however, adding objects to a launched assessment's relationship or reference fields may create clones (or instances) of those objects or merely link them together, depending on the circumstances and if the Assessment Data option is enabled for the corresponding object type.

To check if the Assessment Data option is enabled, review the Workflow tab of the Edit Assessment page. If needed, you can disable this option for one or more object types, add the objects to the assessment, then re-enable the option so that future objects added will have instances created. 

It's not currently possible to add previously assessed objects to an assessment after launch.

For more information on instances and reference data and when instances or links are created, see the Assessment Data & Reference Data article.