SirPrize you are correct, my comment was more of a supportive nature for the pigcat fellow.
Most Tallow and in particular triple milled soaps will not melt well, it can be done, but with only some soaps and even then very carefully. Glycerin soaps are not a problem to melt but for Tallow soaps such as Erasmic (which I believe was your original subject) then I would stick to the Parmesan grater.
The possibility of adding EO’s is an interesting one and unfortunately I think you may only find the answer by trial and error. I do not recall anyone having tried it before. I assume you mean grate the Erasmic and then grate an EO soap, mix them together and hopefully produce the same effect as normal milling but with this new better smelling mixture?
I do not see any reason why it would not work, heating the mix slightly may help the mix bind (heat the container), add a tablespoon of very hot water on top and proceed to tamping the mix down I think should (in theory) do the trick.
Did you have any particular EO in mind to go with the Erasmic?
I would be interested in your results if you try this.