https://www.researchgate.net/post/how_can_we_seprate_ac_and_dc_power_signals_from_a_mixed_dc_with_ac_ripples_power_signal_and_drive_ac_as_well_as_dc_loads_simultaneously
50 V DC plus on overlay of 15 V (amplitude or VSS?) @ 500 Hz ? (Edit: Oh - missed the "RMS". Anyway ...)
AC is easily separated by using some capacitor (1 µF to strt with).
DC separation is somehow 'trickier' as we're dealing with attenuation: You'll need a serious choke plus a serious capacitor. The LC product should be something beyond 1E-6 s. like I fiddled a bit with some simulation (schematics attached) on LTSpice: 2.2 mH and 10.000 µF are nice values - leaving a ripple of some 0.14 VPP for an AC overlay of 30 VPP.
