I don't know about how to get a fighting Grey into a sink, but I have one suggestion. I know others say use cold water and I always did with my birds and they hated the bath/shower/spray. Until one day I tried it with warm water. Now it didn't make too much difference to my Sun Conure, but my TAG changed almost immediately. Now, he still doesn't love the shower, but doesn't yell or fight me at all and tolerates the shower until I take him out - even letting me raise his wings to make sure his back gets soaked. He doesn't play and raise his own wings as others do, but at least it is not a terrible ordeal either.