I have a question about if I made a change to an original image (of my own). For the most part the image has stayed the same, but I ended up redrawing the faces of the character. What is the best way to go about the original e621 upload since they are now similar, but still a bit different. The source file for those images now also link to the new edited one. Should they just get replaced, should they be reuploaded and original is deleted, or in the end should a new upload be made and the original stays?

(Old Parent/Child)
https://e621.net/posts/2508138?q=parent%3A2508138

(New versions)
https://inkbunny.net/s/2292655

Personally, I can see people appreciating both designs, you could probably get away with extra posts.

It's perfectly fine to have both versions up. Both of them look pretty damn good.
As per the uploading guidelines, you are allowed up to 5 variations of any given "base image".