Collating multiple sales orders to combine together on ONE invoice for commercial export

Since Brexit we have had to bulk many customer order numbers onto one sales order. This makes it quite difficult when searching or checking the status of the order as it will not search under 'customer order number' 

It would be fantastic if a customer places 3 or 4 separate orders to collate ONE invoice. This means they could have a sales acknowledgement for each order, not having to add onto one sales order and confusing customer.

Any other suggestions how we can improve this with the current system?