Sorry, Garry, while this might work incidentally, it is not supported. Product documentation reads about Mixing Component Versions:
Mixing Component Versions
The registry and all the underlying components, including DevTest Workstation, must belong to the same release. Mixing component versions under a registry is not supported.
The Enterprise Dashboard is backward compatible through version 8.0 and supports connections from registries of multiple versions. However, the Enterprise Dashboard itself must be the most recent version. For example, Enterprise Dashboard 10.2 can accept connections from 8.0 and 8.4 registries. Enterprise Dashboard 8.4 cannot accept connections from a 10.2 registry.