  Using the two main XTE J1550-564 outbursts (1998-99 and 2000) we gathered
about 30 observations with confirmed detections of HFQPOs. While this is a
small sample it is enough to start looking at the generic properties of these
oscillations, especially focusing on their frequencies and their potential
harmonic relationship. This then will provide us with a list of constraints,
necessary for any attempt of modelling their origin. We defined five groups
based on their similarities in the Fourier domain, namely the continuum of
their power density spectra (PDS) and the HFQPO frequencies. We then combined
the individual PDSs of each family to obtain a PDS with higher statistics to
search for other potential, previously undetected, weaker peaks. While we have
two $3\sigma$ potential detections of a pair of HFQPOs in our combined PDSs,
none of them shows HFQPOs with frequencies in a previously claimed 3:2 ratio.
Using the results presented here we propose an updated list of requirements for
any model trying to explain the HFQPOs in microquasars.
