  Multi-planet systems exhibit a diversity of architectures that diverge from
the solar system and contribute to the topic of exoplanet demographics. Radial
velocity (RV) surveys form a crucial component of exoplanet surveys, as their
long observational baselines allow searches for more distant planetary orbits.
This work provides a significantly revised architecture for the multi-planet
system HD 134606 using both HARPS and UCLES RVs. We confirm the presence of
previously reported planets b, c, and d with periods
$12.0897^{+0.0019}_{-0.0018}$, $58.947^{+0.056}_{-0.054}$, and
$958.7^{+6.3}_{-5.9}$ days, and masses $9.14^{+0.65}_{-0.63}$, $11.0\pm1$, and
$44.5\pm2.9$ Earth masses respectively, with the planet d orbit significantly
revised to over double that originally reported. We report two newly detected
super-Earths, e and f, with periods $4.31943^{+0.00075}_{-0.00068}$ and
$26.9^{+0.019}_{-0.017}$ days, and masses $2.31^{+0.36}_{-0.35}$ and
$5.52^{+0.74}_{-0.73}$ Earth masses, respectively. In addition, we identify a
linear trend in the RV time series, and the cause of this acceleration is
deemed to be a newly detected sub-stellar companion at large separation. HD
134606 now displays four low mass planets in a compact region near the star,
one gas giant further out in the Habitable Zone, an additional massive
companion in the outer regime, and a low mass M dwarf stellar companion at
large separation, making it an intriguing target for system formation/evolution
studies. The location of planet d in the Habitable Zone proves to be an
exciting candidate for future space-based direct imaging missions, whereas
continued RV observations of this system are recommended for understanding the
nature of the massive, long period companion.
