[CAR]

Hmm, maybe I was yesterday wrong, but this has to work (I hope now)

pawn Код:

public OnPlayerConnect(playerid)
{
   for(new i; i<MAX_PLAYERS; i++);
   {
      // Make the players marker an invisible white (chat will be white but marker will be gone).
      SetPlayerMarkerForPlayer(i, playerid, 0xFFFFFF00 );
   }
   return 1;
}

Green text from WIKI^^

And the /backup:

pawn Код:

public OnPlayerCommandText(playerid, cmdtext[])
{
   
   if(!strcmp("/backup", cmdtext, true, 10))
   {
      for(new i; i<MAX_PLAYERS; i++)
      {
         SetPlayerMarkerForPlayer(playerid, i, 0xFF0000); // some color..
      }
      return 1;
   }
   return 0;
}

I hope this will work

Oh and a mapicon, you can maybe move it, but then you need to update the position, so hide, show, hide, show, everytime with another position