  In a population of multiple protostellar systems with discs, the
sub-population of circumbinary discs whose orbital plane is highly misaligned
with respect to the binary's orbital plane constrains the initial distribution
of orbital parameters of the whole population. We show that by measuring the
polar disc fraction and the average orbital eccentricity in the polar discs,
one can constrain the distributions of initial eccentricity and mutual
inclination in multiple stellar systems at birth.
