In Apache NiFi, Is it possible to increase / decrease the scope of a controller?

Changing the scope of existing Controller services is not yet possible in NiFi.

Method-1:

Define a controller service on root canvas level then this controller will be available on all Processor groups, Processors in NiFi instance with Scope as NiFi Flow.

Method-2:

Keep all the processor groups that are going to share same controller service in One Parent Processor group and define controller service on Parent Processor group then the defined controller service will be available to all the processor groups,Processors inside the parent processor group.

Other way:

Defining controller service on all the required processor groups.

There's no current method to do this except the obvious way of recreating it although it would be a nice and convenient feature.

You could suggest it for the next version of NiFi