I have made some smaller additions to the eastern part of the bicycle route named Emscher-Weg. But it is still not complete.

I got a map with a diversion route in Holzwickede from Emschergenossenschaft. This is the organisation which has created the bicycle route and is in charge of it. It might be that OpenStreetMap currently is the only map including that diversion route.

The entry for Emscher-Weg ("EW") on this Wiki page contains helpful links for further work on that route.