ATP wants a single engine add on

Jim Macklin wrote:
The CLT multi-commercial should have been surrendered, do
they both have the same number and name. Have you checked
on the FAA web site for his official ratings?

He's opted out (or he's lying about being a pilot, but I've seen him
walk off a commercial jet in uniform and with ID, so I'm guessing he's
opted out).

I'm guessing that when he got his ATP, he should have surrendered his
commercial but didn't for some reason. I have a feeling it has to do
with his military experience.

So let me get this straight, if he adds on to the commercial (which I
don't think he can do, since he shouldn't have one) it requires the
training and signoffs, but if he adds on to the ATP, it doesn't? Can
you point in me in the right direction for added on ATP ratings?