Show / Hide option in BP detail panel

Hi all,

I am currently working on a BP that is creating trafic signs. In my BP I have a set static mesh with a drop down menu with a enumaration list. This is working fine. Now I want a list with material options specific for that chosen mesh. I already have this working aswell. The problem I have atm is that all the options are visible in the details panel, and I only want the material options visible after chosen the Mesh.

To clarify what I want to do: When placing the BP in the scene there is only 1 option that lets you choose the mesh. After you choose the mesh a new option list becomes visible that lets you choose the material.

Regards, Emile