How to add new variants to an existing Walmart variation group?

Watch out for the Group ID vs Variant Group Name confusion.
Group ID is a number (or alphanumeric) that links the variants together. You make this up yourself.
Variant Group Name is the display name customers see (like "Size/Color").
When adding new variants, make sure the Group ID matches exactly. If you mess that up, they'll show up as separate variation groups.
Also — Walmart's system is case sensitive. "Group123" and "group123" are different. Learned that one the hard way.

You use the same bulk update template. The key is to make sure all your variants (both existing and new) share the same Group ID.
What I do:
Download the current full inventory feed
Keep all existing variants in the file
Add new rows for the new variants
Make sure the Group ID column is the same for all of them
Upload as a full update
If you only upload the new ones without including the old ones, Walmart will sometimes overwrite and drop the old variants. Learned that the hard way.

How to Add New Variants to an Existing Walmart Variation Group
Method 1 – Bulk Upload (Recommended when adding 3 or more new variants)

1. Go to Seller Center → Products → Add Items → Add items in bulk, and download the Full Spec Sheet (or category-specific spec sheet) for your product category.
2. Open the template and add new rows for each new variant. Fill in:

• All required product details (title, description, images, etc.)
• Variant Group ID – use the exact same ID that your existing variation group uses
• Variant attributes (e.g., Size, Color)

1. Save the file and upload it via Update with file. Select Full update to ensure all changes are applied correctly.

Method 2 – Manual Add (Best for adding 1–2 new variants)

• Go to Products → Manage Items in Seller Center.
• Find your existing variation group and click on it.
• Select Manage variants, then click Add variant.
• Fill in the new SKU information (SKU, title, price, attributes, etc.).

Important Notes
Variant Group ID must match exactly – including uppercase/lowercase letters, numbers, and any special characters. If the ID is different, the new variants will not join the existing group and may create a separate variation group instead.
Not sure what your current Group ID is? Here’s how to find it:

• Download an Inventory Report (Reports → Inventory Report). The Group ID will be listed in the “Variant Group ID” column.
• Or open the variation group page in Seller Center – the Group ID often appears in the page URL.

Quick Tips

• If you’re using the bulk upload method, make sure to include your existing variants in the file as well. Uploading only the new ones can sometimes cause the existing variants to drop from the group.
• Walmart’s system is case-sensitive. “Group123” and “group123” are treated as different IDs.
• If your new variants require new attribute values (like a new color), make sure that attribute column exists in your template before uploading.
• GTIN is required for most categories. New variants without a GTIN may upload but will stay in “draft” status with a validation error.