yes, your "theory" about Schaufenberg/Schovenberg sounds really good!
And yes again, I do live in Germany - and if you are interested in geneology and know the places where to search for your ancestors, you can ask to have a look at the old church books there. A friend of mine did so and found out very interesting things about his family.
The town of Hückelhoven has got its own homepage: www.hueckelhoven.de
(maybe Schaufenberg has got one as well...). So you can probably find out something about the churches there.