This paper introduces active brokers and the third-party derivation, the basic programming construct for runtime remote broker deployment, in the ECho/JECho distributed event systems. We describe its implementation in the JECho system and give examples of using it in ECho/JECho distributed event systems. In particular, we describe the use of third-party derivation in supporting the scalability of content-based event delivery. Specifically, third party derivation is used both to dynamically construct content-based event distribution trees and to offload potentially expensive client-specific event routing/processing by runtime creation of remote brokers. Our preliminary benchmark results demonstrate significant benefits of using third-party derivation.