Wilhelm Gerhardt's younger brother Diederich married Hendrikje Jacoba van Baaren in 1878. The couple moved to the Sint Maartensweg in St. Maartensbrug in 1882, along with the photography studio and mother Niestadt. Six years later they moved to Schagen, where Wilhelm took over his brother's shop.
Wilhelm brought his son Wilhelm Heinrich into the business, and they established a branch store in Zuid-Scharwoude (from 1904 to 1909) and later in Medermblik (from 1909). Niestadt Junior moved back and forth between Schagen and the branch store on a motorcycle, one of the very first in the area. A car was soon to follow, to be used for location photography as well. Wilhelm Heinrich married Maaike van Rijswijk from the municipality of Anna Paulowna in 1903. They had three sons, two of whom survived: Wilhelm Diederich (1904) and Lubertie (1914).