####post script####
All of my modwork is not only setting new cultures and portrait.gfx file,but also imploving original AGOT portrait mechanics.
In original AGOT,the clothes of "kingsguard","maestar" and "nightswatch" are inclueded in gfx/characters/XXX_male or XXX_female.dds .
But this structure causes problem...it's incapable to use DLC portrait because of not including these trait based clothes!!
So I found a solution...added new portrait properties.
1.Override defines to "NDefines.NGraphics.NUMBER_OF_PROPERTIES = 15"
2.Add a layer in portraits.gfx: "GFX_custom:14"
3.Create new traitclothes.dds including these 3 clothes and blank
Here is example:westerman.gfx(mixture of lombald face and westernslavic clothes)
portraitType = {
name = "PORTRAIT_westermangfx_male"
effectFile = "gfx/FX/portrait.lua"
layer = { # GFX_TYPE:[d|p]INDEX:COLOR_LINK

ONT_REFRESH_IF_VALID:CULTURE_INDEX
"GFX_character_background

0"
"GFX_westernslavic_male_clothes_behind

3:c0"
"GFX_traitclothes_behind

14"←added
"GFX_westernslavic_male_headgear_behind

5:c1"
"GFX_byzantine_male_hair_behind

1:h:y

3x1"
"GFX_german_male_beard_behind

4

0x-3:h:y"
"GFX_german_male_base

2"
"GFX_german_male_neck:d0"
"GFX_german_male_cheeks:d4"
"GFX_german_male_chin:d1"
"GFX_german_male_mouth:d2"
"GFX_german_male_nose:d3"
"GFX_german_male_eyes:d6"
"GFX_german_male_eyes2:d6:e"
"GFX_character_scars

7:y"
"GFX_character_reddots

8"
"GFX_character_boils

9"
"GFX_character_blinded_eyes

10"
"GFX_character_eyepatch

13:y

30x63"
"GFX_westernslavic_male_clothes

3:c2"
"GFX_traitclothes

14"←added

"GFX_westernslavic_male_headgear_mid

5:c3"
"GFX_german_male_ear:d7"
"GFX_german_male_beard

4

0x-3:h:y"
"GFX_byzantine_male_hair

1:h:y

3x1"
"GFX_character_mask

12:y

40x45"
"GFX_empty

3:c4"
"GFX_westernslavic_male_headgear

5:c5"
"GFX_character_imprisoned

6"
"GFX_player_overlay

11"
}