Field with Dependant Parent Dropdown

Hi All,

I'm looking for some help on Dependant dropdown fields.

In Cases Module I have created a dropdown field (called '1') that is only visible when the Case Sub-Category field is equal to 'A'.

Dropdown field '1' is also the Dependant parent dropdown for MultiSelect field '2' (edit visibility is set).

However MultiSelect field '2' is always visible and I can not see a way to also make this visible only when Sub-Category field is equal to 'A' also. 

Rather than use Dependant option of Parent Dropdown is there a formula I can write that will make MultiSelect field '2' only visible when Sub-Category field is equal to 'A' and also only display specific options depending on the value in Dropdown field '1'?

Hope this makes sense, any help would be appreciated.