What’s the “link programs” setting in Oticon Genie 2?

If you have only setup one program (P1) and no other programs, then the Link-button is not available.

If you have setup more than one programm, then you can “Link” or “Unlink” the programms.
See therefore this thread

Example: You have setup three programms ( P1, P2, P3 ) and want to reduce the volume only in P1 left hearing aid.

Then you first need to seperate ( unlink ) the programms and then select P1 and also seperate (unlink) left side from right side.
After that steps you can reduce the volume for left side in P1 only.

If you did not unlink the programms and did not unlink right from left then the volume change happens in all programms and for left and right simultaniously.