One of my wishlist items was to be able to offset velocity with as a destination so I could do velocity-based element triggering with the assist of a controller. A way to manually "specify" a velocity in order to target specific velocities "at will".

https://www.yamahasynth.com/ask-a-question/can-control-destinations-affect-velocity

This was more about triggering (from the beginning) than mid-stream switching between elements. Which it sounds like is your goal as well.

Glance over BM's response in the link and see if any of that helps you. For me, I had to table the attempt to have Montage react as intended.

Fortunately, the Yamaha engineers did not give up on this.
This is one of the very extremely musical things that can be accomplished with the Motion Control Synthesis Engine. And is one of the creative things you can accomplish with the Super Knob and its Assign Knob System.

Let's make it easy, say I have a string sampled on two levels (P and F). I need two elements in a part. But I don't want to switch between them with keyvelocity, let's say I hold the key while the string_P is being played and then I want to trigger and hear the string_F element of the part with a controller.
I know how to set a (physical) controller (for example modulation wheel or knob) and also how to connect it to the superknob, but how do I switch between the elements with a controller?

As I read your post, you don’t want to use velocity... and this is one of the things that the Motion Control Engine does exquisitely.

Here’s the theory: set up the soft and loud samples so that they both play when you trigger the keyboard, but use the Motion Control Engine to Control when they each sound. Because the synth engine allows you to apply parameter changes in non-linear fashion, you can design the Amplitude change of your Elements..

For example, when the Super Knob is at minimum you’ll hear just the soft sampled Element, as the position changes you hear the loud sampled Element start to come in, at that point the soft sampled Element begins to fade out. This is demonstrated to Grand Effect in the Factory Performances with “Swell” in the name. The timbre of the Hard Strike Elements can be accessed even when the initial velocity is low by using the controller.

This is outlined in great detail using four and five way ‘Element morphing’ (using the Factory Preset “Orch Brass Swell”) in the following step-by-step tutorial article.

Mastering MONTAGE: Orchestra Brass Swell

If after going through it you still have questions, post back here.

Thank you both guys for the response.

@BadMister, thank you for pointing me to the Ochestra Brass Swell. That's exactly what I was looking for. I even remember that there was a tutorial but couldn't remember where to find it. Appreciate that very much. 😉
That's the way how many VSTs change the expression of natural instruments on held notes and I'm glad the Montage is able to do it too!

I had to unpack my Montage and set it up to verify - but if you are not going to hold any given note for more than 8 seconds - you can use key on delay. The max key-on-delay offset will not have an element start until 8 seconds after you strike a key. If you lift the key before 8 seconds - the element will never sound. Any elements that have started sounding will continue to sound even if key-on-delay is changed while the element is sounding.

You would setup superknob to control 2 assignable knobs. I would use user curves at the destination and provide a step function. If the superknob is within a certain range, then make the step-function output value set to maximum (output=127). Make the input values be non-overlapping for each assignable knob so you can have different halfs (if controlling two elements) or quarters (if controlling 4 elements) ... and so on ... change at defined "crossover" points of the superknob.

The assignable knobs can all be set to the same range (low=0, high=127) and spin in the same direction. The destination user curves will determine when the elements are "on" or "off". You need multiple destinations (one per element) so that you can apply a different user curve to each element. Since this is an element-based parameter, each curve is going to un-highlight all but one element.

This can pretty much get you there as long as you don't "sit" on the keyboard for more than 8 seconds. If you do need to "park" - then this won't work and would require another method.