Did you read the official update blog on steam? They give a lot of detailed info there.
Yeah, and the info they give works...or for editing themes. But the problem I have, is that the only way to save an edited theme, is to make a new save...and when you do that, it obviously duplicates the person unnecessarily...so I have to go back and delete the original one that shows up on my roster. And it's not just themes, btw...I've been meaning to ask about this in the past, because it's for any edits that you make to a downloaded character. When you get someone from the workshop, they show up in your roster, but if you edit them at all, then you need to save them as a new character.
Yeah seems to be the only way. A lot of people are taking others creations by doing that too. Once you make a new copy, you can re-upload.