Modify process instance variable via a process model

Hi All,

I have a situation where I work on cases based on process model approach i.e. Assignment in PM itself. Each case goes through 3 levels of approval from associate to manager, to senior manager. I have a master process which triggers when a associate "Smith" starts working on a case, this particular associate will be the assignee for the associate task. Once Smith submits this case it goes to all the managers queue and once they accept the task and submit the case it goes to senior managers queue and once they accept the task and submit the case it comes back to Smith who will close the case finally.

Now let's say we want to change the associate Smith to Alex (Not through reassignment but through another process model). We have to check active process instance for this case and get the process variable that holds the associate name and change that process variable value to Alex.

Is it even possible to modify the process variable of a active process instance through a process model smart services.

Thanks