Editing Process Definitions Safely
Special care needs to be taken when you edit process definitions that have already been submitted and have not yet started or process definitions that have been submitted with a submit frame. This is especially true when you edit the parameter list by adding non-Nullable parameters or by changing a Nullable parameter to non-Nullable. If a process is resubmitted by a submit frame and the parameters are not valid, for example when a non-Nullable parameter contains a null value, the process will be aborted and reach the Modified status, which will require human intervention.
Every time a chain definition is submitted, a branched copy of the chain definition in its current state is made and attached to the process. The user cannot interact with this branched copy. When you edit the master chain definition before the process has reached the Dispatched status, the new chain definition will be used. However, when a chain definition is used several times in a submitted chain definition, the new chain definition will only be used when the first occurrence of the chain process has not reached Dispatched at modification time. This has been implemented to allow chain definitions to remain consistent.