@obj mentioned VRS. If you want to give that a go you might find my Linux VRS guide useful for getting all the bits in place. I can confirm that VRS can be installed on the Pi that’s running PiAware, it works great. I’ve tested it since I wrote the guide.
You’d have to expand the socat feeding methodology a bit to include the 978 data but it should be relatively intuitive to work out and add to vrsfeed (assuming the 978 instance has the raw data on ports the same way as the 1090 instance does). And if you’re on the same network as the Pi when setting up VRS you won’t need the Web Admin access / PluginsConfiguration.txt workaround.
Edited to add:
I’ve remembered that if you’re running VRS on the same Pi as PiAware itself, VRS of course has access to the data from PiAware directly. In that case you don’t need to use socat to push data to VRS, nor do you need vrsfeed to check and launch socat, instead you can just tell VRS to fetch the data from the relevant ports on localhost.
When configuring the Receivers in VRS, instead of configuring them as Push receivers and giving them a free port to listen on, just leave them as normal receivers and tell them the port to fetch the data from. That would normally be:
ADS-B
Address: 127.0.0.1
Port: 30005
MLAT
Address: 127.0.0.1
Port: 30105
Now I’m in the UK and haven’t used the 978 part of PiAware. You mention a second IP address being involved. If you can still access it from the Pi itself then just repeat this process and add the 978 Receivers using whatever address is needed to access the ports on the second IP, eg 127.0.0.2 or whatever is being used. Then merge all four receivers into one Merged receiver and set that as the default on the map.