There are three simple ways to group SKUs together which may be useful:
Kit SKU: A kit SKU is an item created from a number of other sub-SKUs. Once a kit is created, the QOH of each sub-item is automatically adjusted. When a kit is added to a sale you cannot remove sub-items.
Example: a computer assembled from parts which are also sold individually. Once a computer is built, the parts cannot be removed without disassembling the computer itself.
Tag SKU: A tag SKU is used when you wish an item to be automatically added to a sale every time a second item is purchased. You are free to remove the tagged item from a sale if you wish.
Example: A printer cable SKU is tagged in the info for a printer. Whenever a printer is sold, the cable will be added to the transaction, but if the customer does not wish to purchase a cable then it can be removed from the sale.
Basket SKU: A basket SKU is a group of SKUs sold as a single bundle. The quantities of the sub-items are not adjusted until a basket is sold, which will then deduct the amount sold from the QOH of each sub-item. Items cannot be removed from a basket during a transaction.
Example: A jewellery store allows customers to assemble beaded necklaces as a basket SKU containing a number of beads. The necklaces are not pre-assembled, so the quantity of beads is not adjusted until after the necklaces are sold.