How'd you manage to post this out here on the community front page? Move this inside the forums to get an answer.
Here is a solution that involves duplicating your data source and setting up a data blending relationship on the year(Ship Date) = year(Order date) and month(Ship Date) = month(Order Date).
I tried setting up a relationship using Ship Date = Order Date, but since not all days are represented in both fields, it didn't work. If your data source ensures you have all dates for both fields, you can use a simpler relationship.
I also tried to use a dual axis chart with a single data source, but couldn't get it to to show a single line for each metric. See unsuccessful sheet. Perhaps you or someone else can iterate on this solution and get it to show the correct way.
Thanks, once I connected the dates like that I was able to get what I needed. Never would have thought to make a copy and connect the dates, but it works.