Request from the work order
The field order is tied to the ServiceTrade WO, so purchasing is not a separate thread.

Field service
A tech requests material from the ServiceTrade work order. The WO, the cost code, and the date it is needed stay on the order through delivery.
The field order is tied to the ServiceTrade WO, so purchasing is not a separate thread.
The tech sees what is in transit, what is short, and what arrived, without calling the office.
Delivery is confirmed against the order in the field before the vendor bill is trusted.
A thirty-minute walkthrough of this chain on your stack.