If you simply wanted to add an entity rule, I would suggest linking all of the services to a service template that contains this entity rule. Then you could change it whenever you want and it would propagate to all linked services.
Since the entity rule wasn't originally added to the services through a service template, there's no quick way to change it now. I would suggest:
Go through each service manually and remove the old entity rule (with abxxxx).
That way, in the future if you want to change the entity rule again, you can make that once simple change to the template and it'll propagate to all linked services. It's a best practices to use service templates as much as possible when managing lots of services.