Dik -
I do not understand the nature of the question. Unless you are talking about connecting the plate to the beam without transferring some forces between the two. This is possible in two different ways:
1) Use the plate corner releases to dictate which forces can transfer to or from the plate node.
2) Stop your plate short of the beam and fill in the gap with a "link" beam. Set the end releases of the link beam to dictate what forces are transferred between slab and beam.