Virtual Radar can consolidate the view of multiple piawares(I have it doing two at the moment).
If you want to run virtual radar see here (this will get you what you want on Windows 7-10)
ads-b-flight-tracking-f21/ads-b-feeder-project-setup-scripts-t36532.html
It is also possible to make one piaware a master and have the others feed it. Not sure how well this handles MLAT.