AssetPostprocessor and reimporting only some fbx

We use a lot of assetPostProcessor in our game Right now the only way to force a reimport when modifying one is to change the GetVersion() number, but that force a reimport of everything, even FBX that won't be modified by the change. Is there a way to give different version number to different FBX or filter what get reimported? The assetpath variable is null when GetVersion() is called.