Same domain but 2 different entities, Google Merchant Center. Website claiming issue.

What is the best solution to set up Google Merchant Center and Shopping Ads if the main domain and sub-domain belong to different companies?

The sub-domain belongs to our US company, and the main domain belongs to our EU company.

The sub-domain and main domain have different Shopify installs, too.

I tried to set up a different Google Merchant Center account for the main domain (as the sub-domain already has a successful GMC account and Shopping campaigns), but I failed to claim the domain.

How can we set up everything correctly for both companies that both operate on the same domain?

Thanks!

You need to ask the EU company to register and claim https://www.example.com and not https://example.com meaning you need to ask them to register with www

Then in your account you can claim a subdomain.