While I'm waiting for a plumber who apparently isn't coming today, anyway, I'm plugging placenames into the placename search function at www.familysearch.org
Although Welmbuettel (there's an umlaut in my modern atlas) has no records, there are church records just up the road in Tellingstedt.That would appear the likely closest church.Another possibility would be Nordhastedt, and yet another would be . . . . . Albersdorf!
There is also a card index to some of the records in Tellingstedt.
Sometimes you have to turn a lot of dirt for just a little treasure!Just ignore that image of an open pit copper mine.