Possible way to add support for block and item overlay textures

The way I thought how a system for overlay textures could work is the following:
There could be either a checkbox that turns the texture selection from a single selection into a list of textures. The way they are placed in that list then determines which texture is above which, or it could be set using a Z index.
Then, additionally, you could have a checkbox that you can enable to have the texture shown or not, or resolve it using a procedure with a boolean return.
Feedback on this would be great.