As computing environments that combine multiple displays and input devices become more common, the need for applications that take advantage of these capabilities becomes more pressing. However, few applications are designed to support such multi-surface environments. We investigate how to adapt existing applications without access to their source code. We introduce HydraScope, a framework for transforming existing web applications into meta-applications that execute and synchronize multiple copies of applications in parallel, with a multi-user input layer for interacting with it. We describe the Hydra-Scope architecture, validated with five meta-applications.