  Eclipsing binaries remain crucial objects for our understanding of the
universe. In particular, those that are components of multiple systems can help
us solve the problem of the formation of these systems. Analysis of the radial
velocities together with the light curve produced for the first time precise
physical parameters of the components of the multiple systems V773 Cas, QS Aql,
and BR Ind. Their visual orbits were also analyzed, which resulted in slightly
improved orbital elements. What is typical for all these systems is that their
most dominant source is the third distant component. The system V773 Cas
consists of two similar G1-2V stars revolving in a circular orbit and a more
distant component of the A3V type. Additionally, the improved value of parallax
was calculated to be 17.6 mas. Analysis of QS Aql resulted in the following:
the inner eclipsing pair is composed of B6V and F1V stars, and the third
component is of about the B6 spectral type. The outer orbit has high
eccentricity of about 0.95, and observations near its upcoming periastron
passage between the years 2038 and 2040 are of high importance. Also, the
parallax of the system was derived to be about 2.89 mas, moving the star much
closer to the Sun than originally assumed. The system BR Ind was found to be a
quadruple star consisting of two eclipsing K dwarfs orbiting each other with a
period of 1.786 days; the distant component is a single-lined spectroscopic
binary with an orbital period of about 6 days. Both pairs are moving around
each other on their 148 year orbit.
