SEND STANDARD DOCUMENT:agent action and involved parties

How do I setup a loop in custom agent to go through multiple involved parties with same qualifier?

I setup a custom agent that triggers on document upload to the shipment. The agent action send standard document uses a hard coded contact field in the agent action. I did try to setup a saved query to assign a agent variable and then use that variable with send standard document but that will not work when I have a multistop with multiple involved parties with the same involved party qualifier.

I tried using an Automation Agent to assign subscribers to my standard document but this is not being triggered and assigned when the standard document is assigned to my shipment or when I generate the standard document.