Here's an actual lab rat for you guys to dissect:

A couple of months ago, my wife's instructor wanted to get night current
so she could go with my student pilot wife in one of our club planes.
She isn't allowed by the club insurance to fly the airplane alone so I
took her up, as I was current. I flew from the left hand seat; she
wanted to land from the right as she would be doing with students. She
"manipulated the controls" for three landings and we parked it.

I considered myself to be PIC, so not a passenger, but she did the
landings, so regained her currency. She did not "use" her CFII
certificate in the sense of either of us logging it as dual time.

This seemed quite logical to both of us, but of course it is usually
futile to attempt logical analysis of government rules.

Geo. Anderson