Embed an existing graph in an existing graph

So I know how to embed a new graph inside of an existing graph. You just open the tools and then right click on the graph and create a new graph inside. But I would like to take a graph that I have already created (with many curve fits and such applied) and embed it into another graph as an inset. I could remake the graph, but it seems like there should be an easier way to do this.

Thanks!