One Tracking # and Multiple Shipment.

Hello Team,

Can you please let me know the best practice approach for creating EH in SAP EM  system for below scenario.

Scenario  :

Multiple deliveries [eg.Four different Outbound deliveries] are dispatched with one tracking number to the customer , by triggering the event from ECC to EM space in what level EH can be created in a best way? a) Is it based on tracking number or else b) based on each delivery number .

and also , Please give explanation in detail why option a) or b) is not feasible to create the EH in EM.?

Thanks for help.

Siva.