Hi an thank you for your answer.
Unfortunately I guessed something like that :(

Thanks for the description anyway. I know how to add / change the coordinates.

But I asked because I also use Pro-ATC/X and I have chosen to let the program auto-load a new GPS flightplan whenever I got the STAR & Arrival. (so: new GPS Flightplan = new INS Flightplan). - It is not really a complete new plan, but the SID-points have then been deleted and instead the STAR points have been inserted after the last enroute point. So all points from the plan are now changed in position.
I recognized "the problem" when I already was on Page 2  Leg 23 and I got the STAR from ATC which was auto-loaded in the Flightplan.
BUT: the STAR now startet at the end of page 1 and the INS still, of course, was on Page 2 23, which now was in short final of the flight. So I wanted to change the actual waypoint to the correct one which is now on page 1. ...

But now I think, in this case I have to change manually all points whenever Pro-atc loads up the new plan or add the STAR points coordinates manually when I get the correct star... :(

Does anybody know how it was done in the real world with INS!? Did the pilots input all STAR coordinates while they were already descending?

Thanks anyway :)