Steps to replace a page, maintaining internal links

[yjs]

I have a 'Coming soon' page with some basic info and external links (but no internal links and no navbar), currently at index.htm, with corresponding versions for different variants. I also have as 12 separate pages a fully functioning draft site (with corresponding size variants) with internal links and navbar, including a draft homepage of indexnew.htm. I want to replace index.htm (all variants) with the content that's currently at indexnew.htm and I need the links in the other pages (currently pointing to indexnew.htm) to point to that content at its new location (index.htm) in all variants. Grateful for the steps here, as what I'm trying (basically deleting index.htm and renaming indexnew.htm as index.htm) isn't working as expected. Thanks...