Here’s a version of the Osmose “fmdream piano” that does the following:
1. On pressure (before aftertouch the sound will decay like a piano based on the release setting).

2. If you move into the aftertouch the sound will crescendo a bit and be held until you release back across the pressure threshold. When you are in aftertouch you can use the sustain pedal to sustain notes and then you can continue playing in the pressure area using the decay function (so sustain there works more like Sostenuto)

Note: The preset resources were filled up so I had to take away a couple things. The frequency detune offset is gone. The original output scaling was changed to the decay process described above.

Macro Controllers:
Macro Controller Usage
i: (transients) – Controls output of OSC2 ramped envelope and OS4 modulated OSCs.

ii: (trstLength) – Controls attack speed (H) and scaling (Q) of the transient SG envelope

iii: (trstDepth) – Controls amount of transient modulation

iv: (trstFreq) – Control frequency scaling of transients

v: (structure) – Controls BiqBank non-linear frequency spread (a timbre control)

vi: (release) – Control the release/sustain applied to the notes and also determines the global decay time applied to the outputs.

Ped 1: Sustain
Ped2/Mod: Release