Yes.
No matter what the "rule" book says, almost anyone can do anything inside the system.
Many many years ago I used to date a FA - got a great inside look at the bidness.
My parents have gutten Lufthwaffe upgrades and they don't even have FF#'s for that airline - my mom has that attractivive grade-school fear-me vibe that all ex-teachers have and my stepfather is an inveterate upgrade grabber. They do better than I do, and I spend $100K/year on tix.
Look at it this way - if the cashier at Jiffy Lube can get you a free washer fluid fill-up at a franchise location, how hard for a GA to get you into business on an open seat?