The old way (and the only I’m using) is to define several GND symbols but not its name is important but invisible name of pin inside it and then use them as needed.
The new way (since V8 I think) is to put GND symbol and rename it (it didn’t worked previously as it stayed be connected by its invisible pin name to the old net and not by new name).
And then use net-ties to connect your grounds at the point you want.
After reading articles I have linked here:
I rather don’t use star configuration but continuous GND plane like here: