If the Customer the same on all the Sales Order/Shipments you are trying to combine in to one invoice then if so it is possible. 

Need to ensure Bill Seperately is not set on the Sales Order. If you then use the Process Shipment screen and select multiple shipments for the same customer with Bill Seperately unticked then they will be combined in to one Invoice. You could also create the Invocie and use the Add option to add the Sales Order/Line.

Thank@dcomerford, 

Yeah, that process is okay but it does not apply to my scenario. For my case I want to have one Sales Order for Customer A and two separate Shipment for Customer A and B. The invoice should be combined and  billed to Customer A and a separate delivery note for customer A and B.

Can Acumatica help me achieve that?

@helpdesk37 Afraid not the customers must be the same. Your only option i can see would be Customer A is the customer on the Order. You create 2 seperate Shipment and the second Shipment you override the Ship to Address to be Customer B and then you can invoice both to Customer A. It would be a manual process.

Thank you