How to make one collider for parent from children's colliders?

I need to apply a mesh collider for object, bui it consists of other objects with mesh colliders. How can I create just one mesh collider for parent (or create one object from several)?

Good day.

If a Gameobject have a rigidbody component, all its childs with colliders will act as 1 single collider. The rigidbody affect to all childerns colliders.

Bye!