Dave,
The Mind Maps use special connector lines which have a more controlled setup than regular lines. If you reposition a shape, it can be added to another section of the drawing, although you will need to play with the positioning while dragging it around with the mouse, so it can be "grabbed" by the connector line to which you wish to add it. You will see a dotted line appear when the shape is in position to be added to the particular connector branch you wish to move it to and that is when you will want to release your mouse. See if that helps at all.
Regards,
SmartDraw Support