1849-1850 city directory has a Henry Sleep living at 15th & Race. I didn't find him in the previous or following directories, but there is a Henry Sleep in Anderson Twp in the 1870 census, wife Mary, and also a Goldstein in the same household. Wondering if this might be the son of Gerhardt & Wilhelmina. If he is buried at Walnut Hills German Protestant you might find the parents at the Avondale (1st) German Protestant, which was closed to burials around 1864.