All procedurally generated stars in the Milky Way begin in an unchanged installation with 'RS 8474
'. The number '8474
' is the internal serial number of the Milky Way.
If you install a galaxy addon, this serial number changes.
For me in '8485
So if you are looking for any saved star system within the Milky Way, you only need to change the 'RS 8474
-something' in 'RS 8485
-something, and you may find your system again.
Likewise, the serial numbers of all other galaxies change.