Permalinks on a redirected URL

I have a blog hosted with my business website in a folder separate for just the blog. I have another URL redirected to that folder.
(i.e. blog hosted at etmcreative.com, but quilties.com directs to the wordpress folder at etmcreative.com/blog)

Is there a way to make my permalinks say “quilties.com/archives/123”
rather than “etmcreative.com/blog/archives/123”??

I see in the permalinks options page that there is a custom box…can I just type what I want there? Will it work? Are there rules about what can go in that custom box for it to work.