Continuous volume control for samples?

[KontinuumLab]

I've got the sampler working beautifully as a stand-alone sound generator in my new instrument (some of the process is covered in this thread: #48)
The instrument is a digital hand pan, here's some video: https://www.youtube.com/shorts/22rYUG6qyr8

Now I'm trying to get continuous volume control to work, so that cyclic samples, like wind or strings can swell and fade dynamically.
I'm activating notes with Sampler_NoteOn(channel, note, velocity)
How do I then change the volume of the note, without retriggering it?
in "ml_sampler.h" all I could find was this:
void Sampler_ChangeParameter(uint8_t parameter, uint8_t value);
Is there a parameter assigned to volume for samples, or is there another way?
Thanks!