if your are using simple drawing shapes and connectors (and NOT the
"org chart" layout) you can have five boxes above and five below,
slightly offset so that the center of the box below is between the two
boxes above it so your connector can run between them.
that being said, connectors can get fussy if you are constantly moving
or adding things so I would adjust them last, or use lines (line tool)
by right-clicking> edit points and having gridlines set up so that
things fall just right.