Modellng a chain link from a torus primitive? Starting by a torus, I'd like to make the shape of a chain link without touching the torus minor radius.  Saying this I'm excluding the use of scale in object/edit mode, as it will change the minor radius and deform the continuity.

Is there a way to move all 4 link edges symmetrically?

For an End Chain Link (on the right in the picture) it is enough to start with a torus, split it vertically and re-bridge it later.  The Common Chain Link (left in the picture) does have slightly squeezed/angled sides, which I'd prefer to deform/edit once for the one corner and all the others shall just follow the editing, i.e. remain symmetrical along the X-Y-Z axes.
It's not really a scaling operation. It's a translation of half of the torus.



But strictly speaking, to keep a perfectly even profile, you have to duplicate the central edge loops (in the illustration, by splitting the loops, moving one half of the torus, and re-bridging the loops)