You can constrain an object so that its center maintains a constant distance from that of the constraining object.
The centers of the smaller planes maintain a constant distance from that of the constraining object (the large plane).
To constrain an object by distance using the property editor
Choose Constrain 
Distance and pick the object that is to act as a constraint.
In the Distance constraint property editor, set the Distance value, which is a position offset in Softimage units
You can also set position offsets on any axis of the constrained object using the X, Y, Z sliders in the property editor. See Creating Offsets between Constrained and Constraining Objects for more information.
Translate the constraining object. The constrained object also moves, maintaining the distance you set.
