Don't understand why you don't bring Elliott in for Anderson personally. He's in England anyway playing for Leicestershire so would be used to conditions. I understand they would be looking for towards the future and all that but seems a no brainer as a stop gap for this one test to me.
I actually mentioned that to someone today who knows Grant through playing with him. He struggles in the longer form of the game including the 4 day stuff and prefers to stick to the limited overs stuff. The reason is that he has a plan for limited overs as he is a busy player but struggles to find his batting rhythm and therefore form, in the longer versions.