MCreator 2023.3 - Multiple hitboxes for an (Animated) living entity

So basically I'm making a mod that adds a whole new dimensions with new ores, entities, structures etc. And I got to the point where I created a HUGE entity (bigger than the ender dragon ^^'  ) but in MCreator we can't add multiple hitboxes like the ender dragon has. 

So I am wondering if anyone knows how to code multiple hitboxes for a living entity (I ask for code because I'm sure there is no other way to do it). In the title of this forum topic I said "(Animated) living entity" because I suppose this is the same for a classic living entity and a Geckolib animated entity.

I found here someone asking 10 years ago for the ender dragon's model code and there is this thing:

this.body.addBox("body", -12.0F, 0.0F, -16.0F, 24, 24, 64);
this.body.addBox("scale", -1.0F, -6.0F, -10.0F, 2, 6, 12);
this.body.addBox("scale", -1.0F, -6.0F, 10.0F, 2, 6, 12);
this.body.addBox("scale", -1.0F, -6.0F, 30.0F, 2, 6, 12);

I guess this for adding multiple hitboxes for the body only (because there are also "this.wing","this.frontLegTip" etc). But in MCreator, wether it is in the code editor or in the simplified UI, we can only set the hitbox for a cube-like shape (width and depth are a single thing):

Simplified UI:

"Entity model bounding box: (Width/Depth | Height | Shadow Size | Mounted Entity Y Offset)"

Code Editor : Your_EntityRenderer.java:

float scale = 1f;
this.scaleHeight = scale;
this.scaleWidth = scale;

So even with that "this.scaleWidth = scale;" , can we use the @Override somewhere to use maybe the addBox() method ?

I really hope I've been clear enough for you guys to understand what i'm trying to do and why I can't. And I hope Klemen is going to give me an answer because I often see him giving good and working answers :D