  We simulate open clusters containing up to 182 stars initially in the form of
singles, binaries and triples. Due to the high interaction rate a large number
of stable quadruples, quintuples, sextuples, and higher-order hierarchies form
during the course of the simulations. For our choice of initial conditions, the
formation rate of quadruple systems after about 2 Myr is roughly constant with
time at $\sim 0.008$ per cluster per Myr. The formation rate of quintuple and
sextuple systems are about half and one quarter, respectively, of the quadruple
formation rate, and both rates are also approximately constant with time. We
present reaction channels and relative probabilities for the formation of
persistent systems containing up to six stars. The reaction networks for the
formation and destruction of quintuple and sextuple systems can become quite
complicated, although the branching ratios remain largely unchanged during the
course of the cluster evolution. The total number of quadruples is about a
factor of three smaller than observed in the solar neighbourhood.
