  (abridged)Multiple systems for which the astrometric and spectroscopic orbit
are known offer the unique possibility of determining the distance to these
systems directly without any assumptions. They are therefore ideal objects for
a comparison of Gaia data release 3 (GDR3) parallax data, especially since GDR3
presents the results of the non-single star (NSS) analysis that potentially
results in improved parallaxes.
  An sample of 192 orbital parallax determinations for 186 systems is compiled
from the literature. The stars are also potentially in wide binary systems, and
37 candidates were found.
  Only for 21 objects does the NSS analysis provide information, including 8
from the astrometric binary pipeline, for which the parallaxes do improve
significantly compared to those in the main catalogue. It appears that most of
the objects in the sample are eliminated in the pre-filtering stage of the NSS
analysis.
  The difference between the orbital parallax and the (best) \G\ parallax was
finally obtained for 170 objects. When objects with large parallax errors or
unrealistically large differences between the orbital and \G\ parallaxes are
eliminated, and objects with a GOF < 100 or <8 are selected, samples of 68 and
20 stars remain.
  Three recipes that calculate the PZPO are tested. After these corrections are
applied the remaining parallax differences are formally consistent with zero
within the error bar for all three recipes.
  The method of using orbital parallaxes is shown to work, but the full
potential is not reached as an improved parallax from the NSS analysis is
available for only few systems. In the final selection, the orbital parallax of
18 of 20 stars is known to better than 5%. In the full sample, 148 objects
reach this precision and therefore the full potential of using orbital
parallaxes may hopefully be reached with GDR4.
