Change valuelist that is filled by a relation

Is it possible to change a valuelist, that is filled by a relation, which is created with Servoy developer, programmatically with values from another relation? If yes, how? I tried with the following 2 functions, but the values aren’t set to the valuelist:

application.setValueListItems( 'val_schiffname', customersVessels );
elements.tf_vessel.setValueListItems( customersVessels );

The dataset / array customersVessels is not empty.

no setting values only work on custom valluelist
You can’t just set data in a valuelist that is controlled by a relation