In KIT mode, Stylus RMX works like a GM drum sound module with an
instrument or instrument group for each of the 8 channels.
But unfortunatelly, the plugin only gives a single sample per note.

Here is how I proceed to override that...

In this example, I've choosed to create a mini-kit with 4
instruments/instruments groups, 2 samples per note, soft crossfade is
controlled by velocity dynamic of my MIDI input device. I've used my
Trigger Finger :

Here is a global view of my sound selection at mixer page :

Yes we have twice the same kind of instrument, choosen for their similarity, complementarity, second one intended to be a louder (more presence) version of the first one...

Let's see in detail settings for these 2 parts played by the same MIDI note ; the Kick is presented here, others instruments has been tweaked in the same way :

1/for part 1, audible within low to mid velocity values :

A global level ("Level" fader on the left) rather low with an inverted envelope amplitude (orange led under "depth" on the right) : the more the dynamic value of the MIDI note will be,the less audible will the sound be.

- - - AND - - -

2/ for part 2, audible with mid to high velocity values :

An almost basic tweak (blue led under "depth" knob), but with envelope and dynamic sensibility also used/set to the highest possible value.

So, same settings for the 3 other groups (Snare, Hi-Hat, Ride).
For a smoother sample crossfade, filters has been enabled with a 24dB LPF selection.
An alternative could has been using of a LPF+HPF combination with BPF for mid sample, in case of a three level layer, but as we have that polarity parameter for envelope depth value...

As a bonus, I offer to you this "Dynamic Mini-Kit 1" :
that will help you to begin to make your own kits. You only have to drop this file in the "SAGE/StylusRMX/Patches/Kits/User Kits/" folder.

Do not hesitate to tell us about your creations and to propose us your "dynamic kits" !