Cascading Ad-units in DFP Small Business

I have 2 ad units:

1. Homepage banner
2. ROS Banner (r开发者_Python百科un of site)

Basically, I want to find a way to server ROS Banner when Homepage Banner doesn't have anything to serve so the impressions are wasted.

I found this, but was wondering if anyone knew a better way:

http://gam.ingraye.com/cascade/

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Answer, there isn't another way.