Hello topsy,
Wish I could give you great, encouraging news, but I'm afraid I can't. I'm in the same position with my Dreher (later Dryer) family. I'm in Germany & I have a British friend who's in the same position with her husband's family, although she has managed to trace them on the shipping lists. Both our families were from Hanover (which then covered a very big area...not just today's city) & NRW is very big too. That means you could ask their archives to search their church records for you, but there are several thousands of churches involved. If you're very lucky, they might find your family quickly, but it could cost you a fortune & you still might not be able to find them (you can say to them, for example, "Do me 50 Euros worth of searching")
I think the first thing to do is to try to find them on the shipping lists. You might be lucky....there might be a bit more detail. I'll be tied up for the next fortnight, but, soon afterwards, I hope to meet up with my friend who has a record of all the useful sites, so please give me a kick then & I'll pass them on to you.