We would like to use the Field Dependency feature to narrow a multi picklist field's options instead of only being limited to dropdown fields in both the controlling field and the dependent field. For example, one goal is to manage only one (multi picklist) custom field for all applications where access is requested during a new hire request. We would like to use the hiring department (dropdown) field as a controlling field and then select what is available per department from the application access (multi picklist) field.
There are many other possibilities we can think of for using multi picklist fields in Field Dependency, but since it is only limited to dropdown fields we don't use this feature often.