Allow mixed in stock plus pre order purchases in one order

The merchant would like customers to be able to purchase both in stock and pre order quantities of the same product within a single order. For example, if a product has 5 units available and a customer wants to buy 10 units, the customer should be able to purchase the first 5 as normal and automatically place the remaining 5 as pre orders. Currently, Notify Me only shows the pre order option when total inventory reaches zero, so customers cannot combine immediate purchases with additional pre order units in one flow.

This feature would allow stores to seamlessly sell beyond their available stock without interrupting the shopping experience or requiring customers to split their order into multiple steps. It would also help merchants accurately communicate availability while still capturing additional sales.

If this would be helpful for your store as well, please upvote this request!