The Wing dress is independant of the wings themselves.
There is a seprate file to add the wings, it is avataritemdata.txt
(media/resinfo/avataritemdata.txt)
it looks like this:
1 ITEM_MALL_AVATAR_M_ANGEL_WING_DRESS avatar_wing res\item\avatar\avatar_m_angel_wing.bsr 50
1 ITEM_MALL_AVATAR_W_ANGEL_WING_DRESS avatar_wing res\item\avatar\avatar_w_angel_wing.bsr 50
1 ITEM_MALL_AVATAR_M_DEVIL_WING_DRESS avatar_wing res\item\avatar\avatar_m_devil_wing.bsr 50
1 ITEM_MALL_AVATAR_W_DEVIL_WING_DRESS avatar_wing res\item\avatar\avatar_w_devil_wing.bsr 50
just add a line for your suit that u want to have wings... so its the pirate suit in this case.
so add
1 ITEM_MALL_AVATAR_W_PIRATE avatar_wing res\item\avatar\avatar_w_devil_wing.bsr 50
Hope this helps

Happy PK editing.