I’m moving a site off Thrive Theme Builder (cost + lock-in) to a native block theme with my own styles. WP 7.0 stack, theme.json v3.

The site has: blog posts, a few unique one-off pages, and the main marketing pages (home, services, etc.). Some of it was built with Thrive Architect.

My plan so far:

**1.** Build the theme locally — either a child theme of a minimal FSE theme or from scratch with Create Block Theme. Templates, patterns, colors, type scale all defined in theme.json. **2.** Push to staging, activate the new theme with Thrive still active. **3.** Convert pages one at a time, highest-traffic first. **4.** Deactivate Thrive Architect only when nothing depends on it anymore. 

I’m doing it this way because Thrive Architect stores content in post meta, not post_content — so deactivating it early can make content vanish entirely, not just lose its layout. Landing pages seem to be the worst case since they bypass the theme template completely.

What I’m trying to get right:

**•** Where’s the line between “start from scratch” and “child theme a minimal FSE theme”? For a fully custom design, does starting clean actually save time, or do you end up rebuilding what Twenty Twenty-Five already gives you? **•** For blog posts specifically — did Convert to Blocks work for you, or did you end up rebuilding? What broke? **•** Anything that bit you on the SEO side? I have a crawl baseline and CWV numbers saved, but I’m sure there’s something obvious I’m missing. **•** Any reason *not* to run the new theme in production while old pages still render through Architect? That’s the part of my plan I’m least sure about. 

Anyways, looking for advices
Thanks