reducing joined items, chair tutorial

I was watching this chair tutorial and I had some questions because I have used the reducing size step in last part of tutorial and ran into some problems.
The chair tutorial is at http://cter.ed.uiuc.edu/tutorials/SecondLife/chair4.mov
At end he stretches reducing size of the chair.
Reccently whenever I try to reduce or increase size of joined items be something I have made or something someone else has made either two things happen.
Parent changes size but the the shapes attached.
It reduces size only to return later at orginal size.
I figured parent prims only seem to decrease size not the adjoining prims.
I think I am confused.
What going wrong?

Make sure that 'Edit Linked Parts' is NOT checked.

The snap-back or only part changes is usually due to that.

Also, scale it slowly. Move too fast, and parts get out of synch with each other.

I once built an entire 2-story tavern at 1/5 scale. I was able to enlarge it to full size my slowly scaling it up. But if I went too fast, it got messed up.

Thank you Ceera.
Was wondering why it kept resetting it self.
I don't think I had edit linked parks on though.

I noticed in the video the 'take copy' trick to multiply an item. An easier trick is to drag one of the arrows while holding the shift key. It makes a copy of the object (or group of selected or linked objetcs) in the direction of the arrow.