Problem: Related item SKUS not passing to Magento 2. Receiving error: "parameters (4B1185-STD, ME2-HDR6 sku doesn't exist)".
Solution: There are 3 things that are necessary to set a related item in Magento.
- linked_product_sku - (the related sku)
- sku - (the parent sku)
- link_type - (this is if item is "related" or "upsell" etc.)