Like I said, you need to add :kgc_largeparty into the Main Menu Melody.
MENU_COMMANDS =[ # Follow the instructions above.
:items, # Default Item Menu
:status, # Default Status Menu
:skill, # Default Skill Menu
:equip, # Default Equip menu
:event2, # Common Event
:save, # Default Save Menu
:system, # Default Game End Menu
:kgc_largeparty, #Places the Party Command underneath System in Main Menu Melody
] # Do not remove this.
MENU_ICONS ={ # If an icon is not present, it will use the unused icon.
:unused => 176,
:items => 144,
:skill => 159,
:equip => 44,
:status => 137,
:save => 149,
:system => 134,
:kgc_largeparty => 0, #Sets a special Icon for the Party Menu.
I haven't played with the bestiary much though.