TD will help some, yes, but it is most likely vanillin content in the fragrance that causes the discoloration. Other things can cause D too, but vanillin seems to be the most prevalent. You can try a vanilla stabilizer mixed with your fragrance oil before you add it to your soap. Nature's Garden carries one, I believe WSP has 3 different ones depending on the application, I am sure other suppliers carry it too.
Another colorant will turn out looking like color + brown, and that is usually not very pretty.