Material Blend Layer's Scalar Parameter at runtime?

Development Programming & Scripting Blueprint
1

Hello all!

After another week of banging my head against a wall, I thought I saw the light until…
I am trying to trigger switch of material according to a float variable (var_float) for a project of mine.
The constraint is that there are 5 materials to switch between depending on var_float.

I managed to set the logic for that.

But blending between one material to another proves more complex than I could imagine.
I thought I found a solution in using a Material Instance with Blend Layer as simple Alpha to switch between my 5 material Layers.
The idea is to use the Blend Layer scalar parameter for the alpha to display or not the texture if var_float is within a defined range.

That all works: in the Material Instance, I can toggle between 1 and 0 the scalar parameters of the 5 Blend Layers I have for my 5 Materials and they display the way I want.

But now comes the issue: var_float changes on minute basis, so evolves at runtime.
And I want the material to blend and change accordingly.
When I try to get my Blend Layers’ scalar parameters in the Level_BP to set them up with the Create Dynamic Material Instance, my material doesn’t update or change.
Though, I can ‘play’ the project and toggle the Blend Layers’ scalar parameters manually and see the change…

Likely, there is something that I am not properly connecting.
But I also worry, after reading a post from another person here who had a similar (unsolved) issue: can Blend Layer’s scalar parameters be changed at runtime?

If not, does anyone has a possible solution to achieve a blend between multiple materials?

Here is the logic for the display of my material depending on var_float:
mat_1 if var_float = in range (-7.5 to -4.5)
mat_2 if var_float = in range (-6.75 to -0.75)
mat_3 if var_float = in range (-3 to 3)
mat_4 if var_float = in range (0.75 to 6.75)
mat_5 if var_float = in range (4.5 to 7.5)

InkedMat_mat_instance
InkedMat_mat_instance716×796 73.7 KB

The scalar parameters from Blend Layers - that works just fine

Mat_levelbp_scalar parameter
Mat_levelbp_scalar parameter1060×486 67.1 KB

Level_BP, setting up var_float to modify the Blend Layer’s Scalar parameters at runtime

2

After more investigation on this matter, I gathered that one cannot modify Material Blend Layer’s scalar parameter from BP.
A shame, that would have been the ideal solution for what I want to achieve.

Although, I looked into more option and found that using UDIM offers an elegant solution to switch between multiple materials.

My only problem now is to find a way to make a smooth transition between these materials.

It is easy to blend between two material with the blend node.
But in this case, I have 5 materials, and depending on the float_range var that calls the material, I want to be able to transition from mat_1 to mat_4 or mat_5 to mat_3 for example.

I guess one would use the Timeline node in the BP to achieve such thing, although, it isn’t working so well here, as it always starts from a value of 0 (so mat_1 in this case).
Or is there a way that key values can be changed at runtime for the Timeline node?
Any idea on how to organize such a transition?