The easiest is to provide the info they need 80% of the time in the WI text. Then they only need to click the link occasionally.
But what exactly is your process? I'm a bit confused by "once they click yes in the decision they have to refresh their inbox, open a new task, and then open that attachment.". Why not provide the needed object in the first decision?
In a standard decision, there are the buttons at the top, the text below. Then to the right are the objects and attachments. Add your order in there (just bind it in as a container element) and everything is in one step.