I'm a co-author on a poster at the Midwest Archaeological Conference (going on right now) that discusses using the Digital Index of North American Archaeology (DINAA) as a bridge to link independent datasets (including EWHADP data).
Josh Wells was the lead author of the poster, which I have posted here on my academia.edu page. Other co-authors are Eric Kansa, Sarah W. Kansa, Stephen J. Yerka, David G. Anderson, Thaddeus Bissett, Kelsey Noack Meyers, and R. Carl Demuth.
As I discussed here and here, I'm a big fan of seeing what we can do to link open sources of data. It will take some doing to make it into a reality, but it will happen. And it will have a huge upside. Stay tuned!