As best I can tell, this should all be in the rules of building/editing.
Make 8 simple boxes in a row, .5x.5.x.5 is fine. Each about half a meter apart and link it together from right to left, so the lest most prim is the root prim. Looking something like this:
[ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ]
So you have an object, well within the max size limits.
Now, select edit linked part, and stretch. Go to the furthest right prim, furthest from the root prim, and play with the scale within normal parameters, even at minimum size, it should be well within the normal diagonal length +1 rule for each one. After a little playing this prim, every time I have tried it, becomes 'bouncy' it will spring back to a size and allow no further editing of any sort. Now, move left down the line, doing the same to each prim except the root. Now and again it will spontaneously fix itself, so you may have to start again, but by the time you get to the end. You now have a object where edit linked part is completely useless, no changes can be made to it.
Now, what is really messing me up, is the same thing happens with llSetScale/Pos. A script that alters the object it is in, will simply stop working with no remedy but taking the object and re-rezzing it every time.
Is there another remedy for this?