OK, try this:
Select the sphere tool and save it with a new name, something like ‘center.ztl’.
This will help place your pieces.
Start MarkerMaster and make sure the red dot is in the middle of the canvas. Also make sure ‘AutoMarking’ is OFF.
Select your ‘center’ tool and draw it on the canvas, not too close to the red dot. Press ‘M’ on the keyboard to mark it. In the Markers palette, switch off the Tool button. Now select the ‘body’ piece and click on the ‘center’ (sphere) marker. Move the body down a bit and mark it by pressing ‘M’. Repeat this for the other tow parts making sure the markers aren’t too close (though you can get pretty close).
When you’ve placed and marker all the parts, select the ‘center.ztl’ again and save it with a new name. It doesn’t matter what.
Having done all the above, click on the ‘Group’ button.
EDIT: actually, having tried this it doesn’t work as I expected. 
The tools get swapped all the same! Your best bet is to not use markers to place your objects - use the gyro instead to move them into a reasonable alignment then use the Group in Edit mode to adjust them.
