Detect subtask change from parent point of view

Hello,

 I try to create a workflow that will change the state of a parent given the state of the child which is not in the same project.

So let say I want to apply this rules on a Project A.

Some of my subtasks belong to Project B. If any subtasks referring to a parent in project A change then I want to apply some change on this parent.

Today I just find how to detect my changes in a given issues, which mean that I must apply my workflow to every project in my youtrack instance and that this workflow need to be very specific (check if parent belong to project A, so if I want to reapply this workflow to another project, I must duplicate it).

Is there a way to detect when a substask of a given project change even if this issue doesn't belong to the project? (I thought of a way to do it : schedule a workflow instead of checkinf "in real time" but perheaps is the a better way)