In Google Merchant Center, on the Feeds Tab, you can click on the feed registered by Squarespace, and then click the "Settings" tab.
On the "Settings" tab, under the "Target countries, language, and destinations" section, click the pencil icon next to the "United States" label. Select any additional countries like UK, and then click "Save".
I haven't tried it with the built-in Squarespace Google feed, but this should allow you to assign additional English-speaking countries (like UK, Australia, Canada) to the existing feed.
Can someone try this and post here if it works or not?
