A PartDecomposition cannot receive ‘create’ or ‘destroy’ Messages.
A PartDecomposition is the description of the internal interactions of one Lifeline relative to an Interaction.
A Lifeline has a Class associated as the type of the Instance that the Lifeline represents. That Class may have an internal structure and the PartDecomposition is an Interaction that describes the behavior of that internal structure relative to the Interaction where the decomposition is referenced.
If you encounter an R1830 error, delete the incriminated Messages.