useAutoMass and child objects

Hello! Question is:
I have an object with rigidbody2d, and useAutoMass checked.

Then I instantiate a bunch of prefabs, with colliders, but without rigidbodies, and make my main object their parent.

I assigned density for children prefabs by adding rigidbody, checking useAutoMass, assigning density, and then removing rigidbody
Their density do not work, when I instantiate them. When I pause my scene, all numbers are there, as I wanted them to, but they work as if they have default density. They start to work properly after I reassign density to them, like this: Collider.density = Collider.density; but I wonder if there are less messy way to make it all work?

Collider2D without a Rigidbody2D are static and don’t move therefore mass is irrelevant and density is not used or at least it goes back to the default of 1.

Only colliders attached to a dynamic body use density.

I’m not even sure I follow what you’re trying to do.