Products can be configured as "related" to other products.
This is typically used as an internal reference that can be used for looking up similar products. (You will not be able to scan and ship a related product. You can scan and ship a replacement product.)
However, using a custom calc/plugin, inventory can be pulled from related products to update a listing on a channel. The custom inventory calc can be created by the SellerCloud Development team and is subject to customization rates.
Import Related Products
Catalog Management >