I just ordered an embroidery machine. Haven't gotten it delivered yet but it has this software included with it.
Floriani Thread Converter Pro III software.
Your thread choices will never be limited. In just a few clicks this color conversion software changes to and from 14 different thread manufacturers. You can use all of your thread inventory! It is simple to convert one or more colors within a single design.
I don't know if its available as an individual purchase but you could do a search for it.