Pawn Switching, I need it to switch only between my main party members, not the whole map.

It stops at the end of the index because you never set index back to 0 after it reached the max value.
As Kontur said you are able to posses every pawn in your game because you do not limit the selection of “get all actors of class”. If you have a different Blueprint class for your party members use that instead of pawn.

Regards