Drawing Substitution Issue


I have a character in a project that I need to replace his hands with the hands of a character from another project.
So I moved the hand drawings to the library in order to have them in the project that I need.
But I can’t find a way t make the drawing substitution. Since the hands are not showing as a drawing substitution option.

What can I do in that case?
How can I put drawings from the library in the drawing substitution box?