Tricky modelling in STAAD

So, I attached two pictures, the hand drafted shows what I'm trying to achieve in STAAD. I'm not facing problem with the beams, those are already modeled, but how am I supposed to go about the plates at level 0.00?

Note that only the beam in red has an offset at one end at -1, this is what makes placing the plates tricky. The beam in red has a depth less than that supporting the 1.00 slab. The perpendicular beams are flashing at the bottom.

Any suggestions?

One approach I tried was to have all the beams modeled at 1.00, then model the plates, then give the beams supporting the lower slab a -1 offset at both ends, but is this a correct approach specially that the nodes of the plates are still at 1.00?