How can I add the current and historical hierarchy in my dashboard hierarchy filter?

I have 2 surveys mapped under one dashboard, the historical survey and the current survey. I have mapped both hierarchies but when I try to use both hierarchies in my hierarchy filter I am able to see only the hierarchy of the current survey. Am I missing something?
The purpose of having both hierarchies under the hierarchy filter is to use them to to filter and display previous survey data and current survey data.
Thanks,