I defined several participant types for my case type. The party "LeistungsAuditor" is set to be a party that may repeat.

To add new participants I can use the Participants section in the lower right corner. A click on the wheel will open a modal dialog and executes the flow action pyUpdateWorkParties which consists of many activities. Using this way I am able to add more than one LeistungsAuditor to the list. In clipboard it will be listed as pyWorkParty(LeistungsAuditor_02) or pyWorkParty(LeistungsAuditor_03). 

Now I want to update this participant list automatically whenever I add a new LeistungsAuditor in a row entry in a certain table. As the table runs in Data-Class I use the refresh condition to trigger a Data transform in Work-Class. 

Executing this DT runs well for the FIRST time, a new LeistungsAuditor will be added to Particpants list. However when I want to another LeistungsAuditor, then it will update the first entry and copy the initial entry to LeistungsAuditor_02 and dismisses all the Operator data (see pic 4).

Is there any way to overcome this problem with OOTB functionality? I used activity PartyAddOperator, but this only updates the party LeistungsAuditor with the latest person I add. There won't be any new party created.

Using the pyUpdateWorkParties activity won't work, as it is expecting to show the list of all participant types. 

See my pics for better understanding.