This feature works if you sell MF only. If you sell FBA, this option will not work you.
This is a setting found on your Amazon integrations page. Listing Mirror will send your Amazon listings to all of the marketplaces that are enabled.
If you are already selling on Amazon US and want to start selling on Amazon MX/CA and you have the ability to ship there! (or vice versa)
Go to the integrations page for Amazon.
At the bottom of the page, you can find the Sync Marketplaces setting.
Check off the marketplaces you want to send your Amazon listings to.
And that's all you have to do!