Below shows how I set the permissions for both the Category and Sub-Category. I set the same permissions for both.

Even though Special Contributor is permitted to add pictures to both categories, Special Contributors are not able to add photos to the Sub-Category. The option does not show on the drop down menu of categories when adding a photo. They can only add a photo to the main Category.
The only way it is possible for them to add pictures to this Sub-Category is if in the main Member Group permissions I allow them Admin access to SMF Gallery in general. But if I do this then can also delete pictures and it gives them too much control, so it is not a good solution.
Please advise a solution. Thanks.