Has Etabs v19 got a method for using null areas for load assignments. I remember using this tool in v18.0.1 but this function seems to have discontinued.
You can still use Null area to assign superimposed loads on top of structural slab or deck. See proof below.
A2 is null area 6x6 loaded 100psf. F2 is one-way load distribution deck.
Here is the caveat: This works wonder if you model everything in coordinate system with System Origin Rotation = 0. If it is rotated, ETABS will f.ck it up. Check it out yourself.