Change item number in estimate screen without removing other information?

Does anyone know of a way to adjust a sales estimate - in particular, edit the item number - without removing all other information from the line? An edit to the item number is removing the quantity, description, price, etc. 

Prior to adjusting the entry:

After adjusting the entry:

Any and all advice would be greatly appreciated! Our estimators went through a numbering change and are struggling with the tedium of retyping all of their quotes.