No need to uninstall ver 6.1.
After adding my repository for ver 7.0 (first 3 commands of How-To), issue command sudo apt install piaware and sudo apt install dump1090-fa. The apt is smart, and will install latest version 7.0 over old version 6.1, and all your configurations (feeder-id, gain setting, etc) for ver 6.1 will be transferred to ver 7.0 
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