I am not sure this is even possible, although it should be.
I use 4 external editors from Lightroom -- Photoshop and three Topaz products. I want each externally edited wile to have a suffix added that identifies which editor was used. So, filename-PS.tif for Photoshop, filename-TD.tif for Topaz denoise, and soon. The best I have been able to do is have the same suffix for all external editors. Is what I want possible?