  We suggest and analyze a novel technique for efficient and robust creation of
dense ultracold molecular ensembles in their ground rovibrational state. In our
approach a molecule is brought to the ground state through a series of
intermediate vibrational states via a {\em multistate chainwise Stimulated
Raman Adiabatic Passage} (c-STIRAP) technique. We study the influence of the
intermediate states decay on the transfer process and suggest an approach that
minimizes the population of these states, resulting in a maximal transfer
efficiency. As an example, we analyze the formation of $^{87}$Rb$_{2}$ starting
from an initial Feshbach molecular state and taking into account major decay
mechanisms due to inelastic atom-molecule and molecule-molecule collisions.
Numerical analysis suggests a transfer efficiency $>$ 90%, even in the presence
of strong collisional relaxation as are present in a high density atomic gas.
