How to specify different form for specfic Request Model

We are on Service Manager v9.52 using Process Designer.  For most Request Models on the Logging phase we have a default form listed and then another default form under Additional Forms when the condition is $L.mode="add".  (see attached)

I have a need to specify a different form if the request model is one specific request model.  I can't seem to get that to work, it will use the same for for ALL request models.  How can I write the conidtion do that when the user clicks this one specific request model, a different form will open other than the default that is used for all other request models?