[css-grid] Question regarding the layering of elements assigned to the same grid-area

Hello,
I've started working with grid layout, when assigning multiple elements to
the same grid area they layer. I understand that this is the intended use.
Has there been any consideration of a property that would allow multiple
elements assigned to the same grid area to display in a block formatting
context? I can imagine a responsive design having more grid areas in a
large desktop layout than it does a mobile layout. It might be desirable to
have multiple grid items laid out in a grid area.