  The Relativistic Hartree Bogoliubov model in coordinate space, with finite
range pairing interaction, is applied to the description of
$\Lambda$-hypernuclei with a large neutron excess. The addition of the
$\Lambda$ hyperon to Ne isotopes with neutron halo can shift the neutron drip
by stabilizing an otherwise unbound core nucleus. The additional binding of the
halo neutrons to the core originates from the increase in magnitude of the
spin-orbit term. Although the $\Lambda$ produces only a fractional change in
the central mean-field potential, through a purely relativistic effect it
increases the spin-orbit term which binds the outermost neutrons.
