Generate multiple Normal Map textures and assign to Materials from Albedo at Object Import

I have a rather complex .fbx that I generated procedurally in an external program - It exports FBX but the Materials and textures only show up with Albedo when imported into unity - Id like to generate normal map textures from the albedo for all of the materials in the editor - is there a way to batch? - there's over 250 materials- Manually duplicating and assigning the textures to the normal map slot in each of the different materials doesn't seem like the right way to go.,