can't make physics constraints component child class ?

I wanted to make an object that consists of a bunch of static meshes constrained together

I’m using physic constraint components to lock them together.

I want to lock perfectly my meshes together (absolutely no liberty in any axis)

The meshes are created at runtime, so I cannot set the physic constraint component’s parameters manually

I tried spawning it using blueprints, but it gives a slight liberty to my meshes (as there is this “projection tolerance” thing enabled by default)

I doesn’t seem like I can change the “projection tolerance” of an already spawned physic constraint component trough blueprints, so I though I could make a blueprint class whose parent is “physics constraint component”, set the projection tolerance to 0 in the class defaults, and use this component instead, but I can’t make a child of this class either…

Is there a way to get rid of the projection tolerance at runtime/to make a child of “physics constraint component” (and why can’t I simply make a child of that component like I can with any other blueprint class ?)