Bringing extra folks to an ADR at Grand Floridian Cafe: maybe. Brining extra folks to an ADR at Le Cellier: I wouldn't do it because I'd be afraid that the group would be disappointed and hungry, never a good combination!
I agree with a PP: your best bet is going to be stalking the dining ressie site for a cancellation. The credit card guarantee could work to your advantage and you may be able to snag an ADR that someone doesn't want at the last minute.
or...
For alternatives, I checked the Disney dining site. I hear the steaks are wonderful at Yachtsman, and they have table available for 9. There are many locations (39) with tables open for a large party of 9. You may not get your first choice of Le Cellier, but if it were me I'd rather know that my big group could eat together at a place of my choosing rather than trying for a walk-up that will likely not happen.