Update all child-object positions automatically?

I have hundreds of objects, which are children.
Their parents are repositioned, while those children are not visible.
Now, when I switch them to visible, they are all still in their old positions.
When I manually “touch” their transform, they update/reposition themselves.

Is there a way to do this automatically, through python?
One way would be to search these objects, then transform them by some very small amount.
But is there an easier way?
bpy.context.scene.update() does not do anything here.