The stock that runs out during BFCM is rarely the product you promoted.
Offer mechanics consume stock in patterns your forecast does not describe, because demand for a gift is driven by sales of something else.
Continue-selling-when-out-of-stock is safe all year and dangerous during BFCM, when weeks of ordering compress into hours.
Decide before the weekend what each offer does when its component runs out, because the alternative is deciding it at 2am.
Fulfilment capacity is a hard constraint, and extending the sale window is the cheapest way to spread the load.
Because demand for a bundle component is driven by sales of the anchor product, not by its own standalone demand.
The full guide has the formats, the deadlines and the worked examples.