I have tested Paul's suggestion (convert to triax, save changes, replace morphs), and I can't make it work. I copy the morphs, fix the paths, but when I load the figure, the new morphs won't show up. In addition, DS crashes when I close the program. I have tried restarting DS, for maybe it was caching the existing morphs, but the changes still won't show. That was my last option to make this work in DS.
Before I even tried to do all this, my beta-testers were already saying the issues were easy to adjust, and there weren't many anyway. They said they didn't mind it, and extra instructions on the documentation should suffice. But I am a perfectionist, and wanted to have it fixed the "proper" way - just to find out that it can't be fixed. Paul was telling me I should had started this on DS, but it was done 2 years ago and I had no intention of ever selling it. It was for personal use.
One reason I wouldn't want to start things in DS is the fact that it doesn't have anything to help creating morphs, like for example the Morphing Tool in Poser. We have to go work in another programs, such as ZBrush, and then go back to configure it on the figure. In Poser I can do everything without leaving the program. Even though the Morphing Tool is not as good as ZBrush, it has dedicated tools that are specialized on content creation that ZB doesn't have, like the conforming brush. That alone can do things that ZB can't, and it saves a lot of time. Not to mention the times when morphs look different after imported back in Poser.
The funny thing was that I thought the head should work great in DS since this figure doesn't use weight maps, but I was not counting on ERC incompatibilities. If anything, I have learned something new with this experience. ^^
The only alternative is do leave it alone and add more info on the ReadMe file.