The founder Nicolaus III Gercken (1555 – 1610) stipulated in his will, that the income of his endowment ought to benefit the descendants of his grandfather, Nicolaus I Gercken (1501 – 1579). Nicolaus I Gercken had three sons and six daughters. The founder had no children. Known today are five surviving family branches. Each one of them is denoted with a letter. Today more than 230 individuals are registered as family members.