Byline: By GRACE MACASKILL
ALLY McCOIST has been a football legend to little Jack Rice for all of his seven short years.
Now the Scotland legend could be the hero who helps save his life.
The Rangers assistant manager is begging Scots to join the bone marrow transplant register to give Jack the chance of survival as he fights a rare disease.
Jack suffers from a severe form of aplastic anaemia, which means his body can not produce blood cells to fight infection or control bleeding.
He has been in isolation at the Sick Kids Hospital at Yorkhill, Glasgow, for the last three weeks and doctors say he could die without a transplant.
Ally, 45, said: "Jack is a very special wee boy. His strength and …