Reserving Inventory For Customer Sales Orders

Hello, I am not an SD Expert. My background is MM/PTP/LE/IM. Currently, I have a scenario as follows:

1. Sales order is entered to pull inventory from stock
2. Inventory is made in house
3. Orders are being confirmed by order date

However, we have situation where an order with an older date has a larger quantity (let's say 5). Subsequent orders are for units of 1-2. As we produced the goods and put it into inventory the orders with the lower quantities are getting filled. Thus we keep pushing the date out to the future for the order with the older date.

Right now, I have instructed the team to protect the units by moving to blocked stock. My questions is this. Is there anything we can do within the backorder/rescheduling process to protect the inventory ? Do we need to look at product allocation functionality?

Thanks......