Can the address change tool be used to merge two websites?

What is the actual function of the address change tool?

The address change tool in Search Console allows you to inform Google that an entire site is moving from domain A to domain B. The idea is to expedite the recognition of this migration by explicitly signaling that all the pages from the old domain now have an equivalent on the new one. It’s a kind of priority signal sent to crawlers.

But here’s the catch: this tool only works for a complete domain change. It is not designed to handle cases where you merge site-a.com and site-b.com into site-c.com, nor to move a section from site-a.com/blog/ to site-b.com/resources/. Google expects a 1:1 match between the old and new domains.

Why can’t site merging use this tool?

Merging two sites generally means redirecting content from multiple sources to a single destination domain. However, the address change tool only supports one source domain. If you try to declare site-a.com to site-c.com, and then site-b.com to site-c.com, Google won't be able to manage the conflict.

Furthermore, a merge often involves content regroupings, deletions, and consolidations. The address change tool expects each URL from the old domain to redirect to an equivalent URL from the new domain, purely in a migration context. No merging, no reorganization: just a relocation.

How does Google handle site mergers then?

Google relies on standard crawling and 301 redirects to understand when content has been moved or merged. When Googlebot encounters a permanent redirect, it gradually transfers signals from the old URL to the new one (backlinks, history, authority). There are no shortcuts, no magic buttons.

For a successful merge, you must manually map each source URL to its target destination, implement the redirects, ensure that the new URLs are crawlable, and then allow time for Google to reprocess everything. Patience is essential: depending on the size of the site, this can take several weeks.

• The address change tool works only for a complete domain migrating to another complete domain.
• Merging multiple sites requires manual 301 redirects and precise URL mapping.
• Google detects mergers via natural crawling, not through a dedicated tool in Search Console.
• Do not attempt to circumvent this limitation by declaring multiple address changes simultaneously: it creates confusion.
• A well-executed merge gradually transfers SEO signals, but it requires time and diligence.

Is this statement consistent with real-world observations?

Yes, and that's rather reassuring. In practice, attempts to use the address change tool for partial or multiple mergers generally result in unexpected de-indexations, ranking fluctuations, or misinterpreted redirects. Google has always been clear on this point, even if some still hope for a shortcut.

What’s missing in this statement is a detailed explanation of what happens if the tool is abused. Does Google simply cancel the request? Does it penalize the site? Does it ignore the redirects? [To verify]: no official documentation details the consequences of inappropriate use of this tool.

What nuances should be applied to this rule?

Mueller's statement does not cover cases of subdomain to subdomain migrations. Technically, blog.site-a.com to blog.site-b.com could be considered a complete domain change if the subdomain is treated as a distinct entity. But again, Google remains vague.

Another gray area involves HTTPS migrations or URL structure changes without a domain change. The address change tool does not apply, but Search Console offers other signals (separate HTTPS property, internal redirects). The risk is believing that everything can be explicitly reported to Google, while most migrations are managed via natural crawling.

In what cases does this rule pose problems?

For large sites merging several brands or various geographic domains, the lack of a dedicated tool complicates matters. Imagine a company with site-fr.com, site-de.com, site-es.com wanting to consolidate everything into site.com/fr/, /de/, /es/. It is impossible to use the address change tool to signal these three simultaneous migrations.

In this case, one must rely on a rigorous mapping, massive 301 redirects, and closely monitor crawl logs to ensure that Google is accurately following the redirects. This process is cumbersome, time-consuming, and prone to errors if the mapping is incomplete. [To verify]: Google might propose a dedicated site merger tool, but nothing has been announced to date.

What should you do practically to merge two sites?

The first step is to create a complete mapping between the source site URLs and the destination site URLs. Each page from site-a.com and site-b.com must have a corresponding match on site-c.com. If certain pages do not have a direct equivalent, redirect to the most relevant page or to a thematic hub page.

Next, implement 301 redirects on the old domains. Verify that the redirects are permanent (HTTP status 301, not 302), and that they do not go through redirect chains. Google can follow chains, but each jump dilutes the ranking signals.

What mistakes to avoid during a site merge?

Never redirect all URLs from the old domain to the homepage of the new domain. This guarantees loss of some organic traffic and dilution of authority. Google interprets these redirects as a soft 404 if the target content is not relevant.

Another trap: neglecting the backlinks. If site-a.com has quality links pointing to specific pages, ensure that these pages redirect to equivalent content on site-c.com. Otherwise, you lose the benefits of those links. Also, keep an eye on the link anchors: if they point to content that disappears, the impact is negative.

How to check if the merge is going smoothly?

Use coverage and performance reports in Search Console to track progress. You should see a gradual decline in impressions and clicks on the old domains, and an equivalent rise on the destination domain. If the two curves do not intersect, there is an issue.

Also, monitor the crawl logs: Google must crawl the old URLs, detect the 301 redirects, and then crawl the new target URLs. If the bot remains stuck on the old URLs without following the redirects, it indicates a technical configuration is blocking the passage (robots.txt, server error, too long redirect chain).

• Create comprehensive URL-by-URL mapping between source sites and the destination site.
• Implement permanent 301 redirects without chains or loops.
• Never redirect all URLs to the homepage: maintain thematic relevance.
• Monitor backlinks and ensure that target pages receive the ranking signals properly.
• Track progress in Search Console (coverage, performance, crawl logs) for at least 3 months.
• Test redirects in real conditions with a crawler (Screaming Frog, OnCrawl) before going live.