1. Delete obsolete matrix parents
  2. Inventory > Saved Searches: Non Shadow Only
  3. Search for item > Select all pages > Export Products to Excel
  4. Copy relevant Product IDs
  5. Google Listings Sheet: Paste SKU list into SKU/UPC tab
  6. Enter color name(s) in INPUT tab
  7. Parent Child Import tab > download as CSV
  8. SC Import Product N Matrix page > upload file