Can I add a new variant to an existing product in Squarespace?

Yes, you can add a new variant to an existing product that is already published on your Squarespace store. Add the new Variant in Squarespace.

1. Firstly, create the new variant manually in Squarespace. You can do this by going to Commerce > Inventory 
   
2. Click on the selected product
   
3. Click on Manage option in the top right corner and Add option provide the name of the new variant and click on Save.

The steps might differ, depending on whether you are using Squarespace's new or classic product editor. You can read more about this in Squarespace's Help Center article Adding product variants.

Sync products in Gelato

Once the new variation is created in Squarespace, navigate to the Stores section and select your Squarespace store. Click on the "Sync products" button located on the top right of the page.

After a while, you will see a new variant as "Not connected".

Connect the new variation in Gelato

You will now be able to connect the new variation to a product in Gelato as shown here. 

If you need to add many variants, it might be faster to create the product from scratch by following the steps described here.