Hello, feage7!

I'm embarrassed . . . It's even simpler than I thought.

Note that the answer has: .$\displaystyle (a-b)^2(b-c)^2(a-c)^2$

Since all those factors aresquared, the order of subtraction doesn't matter!

. . That is: .$\displaystyle (b-a)^2 = (a-b)^2$, etc.

So I didn't have to do any "switching" . . .