I need a way to set a variable in Task Listeners and Invoke Conditional Message Event

I have a parallel subprocess,
upon user claim(assignment change) of every user task within parallel instance I need to run script task
to achieve this I have added a task listener which will set a variable within the scope of the instance and also added a conditional message boundary event to track the variable changes event, but I am not sure how to create a variable in the scope of individual instance within the parallel flow

found a solution, I used a task listener on the user task and triggering a signal boundary event
Task Listener script :-
var signalName = “UserClaimed”;
var executionId = task.execution.getId();
task.execution.setVariable(loopCounter, task.assignee);
task.execution.getProcessEngineServices().getRuntimeService().signalEventReceived(signalName,executionId );