You are still not allowed to chain a VSTi after a VST or VSTi in Biab though it was asked for years n years so you need to use Element VST this will allow you to do modern routing and use either VST2 or VST3 in it, plugins can be easily added with a simple right click, or drag n drop from folder (if Biab is not running as administrator)
If you load the EZDrummer VST then after it put the Sforzando VST with a RealDrums SFZ turn the volume down on EZDrummer and set it to Midi Out.
Element VST
element-win64
element-osx

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This is the hook up guide, just drag from orange or green points to connect and drag cable to dissconnect, make sure you have the EXT sync enabled in top left, if you right click the VST and Save Group it will all load each time without having to set it all up again. You can do the same with EZKeys EZBass, even use them for Playable RealTracks sections:

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