Billable references

We implement a billing system based on unique reference IDs, with the exception being that the creation of a parent reference based on a provided bill of lading is not billable.

To provide an example, a bill of lading that is used to track 10 containers will count as 10 active references only. The parent reference is used as a base to determine how many containers need to be tracked and each child reference will have its own unique reference ID.