Since the sub and mains are all fully independent channels, any channel you want to equalize requires a dedicated equalizer. If you want everything in one unit, that would require a multi-channel equalizer like the AudioControl Bijou or Diva or the Rane Home Cinema equalizers. Most people...
The only problem would be if one of the low spots is a null, but it doesn’t appear that that’s the case with your curve. Still, you won’t know for sure until you try. Keep in mind that the BFD will only adjust below and perhaps a little above the crossover point. Regards, Wayne A. Pflughaupt