I wonder how combining 2 GPS satellites with 2 Galileo satellites would work in a realtime setting. As far as I know, GPS and Galileo have a different timebase

I wonder how combining 2 GPS satellites with 2 Galileo satellites would work in a realtime setting. As far as I know, GPS and Galileo have a different timebase. If you don't know the time difference, you can be way off.