So at great length and a ridiculous amount of work, I've been able to finish working out the borders of the Regional Districts and Indigenous Administrative Districts.

Please note that there are a bunch of small exclaves that aren't shown here, for being too small; for example, the city of Burns Lake is in Bulkley-Nechako RD, but some neighbourhoods are part of the Dakelh Federation IAD. There are a bunch of other such occurrences, particularly in the big cities. Utari Mosir is also not shown on this map. I don't know why, but drawing maps is a lot of fun.
Indigenous Administrative DistrictsEach has a representative in the Council of Chiefs, except for the Ainu.
Champagne Aishihik Nation - seat: Nuqwaʼik-Àłsêxh (Southern Tutchone)
Dakelh Federation - seat: Tsetlʼadak (Cheslatta) (Dakelh)
Ditidaht Nation - seat: Ditidaht (Ditidaht)
Gitxsan Nation - seat: Hagwilget (Gitxsan)
Haida Gwaii - seat: Hlg̱aagilda (Skidegate) (Haida)
Haíɫzaqv Nation - seat: Bella Bella (Heiltsuk)
Haisla Nation - seat: Haisla (Haisla)
Kaska Dena - seat: Good Hope Lake (Kaska)
Ktunaxa Nation - seat: Yaqan Nuʔkiy (Ktunaxa (Kootenay))
Kwakwewlth District - seat: Weywakum (Campbell River) (Kwakwakaʼwakw)
Łingít Nation - seat: Wéinaa (Atlin) (Tlingit)
Nautʼsa mawt Nation - seat: Xwémalhkwu (Campbell River) (Several)
Nisgaʼa Lisims - seat: Gitlaxtʼaamiks (Nisgaʼa)
Nlakaʼpamux Nation - seat: Boston Bar (Nlakaʼpamux)
Northern Rockies Territory - seat: Fort Nelson (Dene, Cree)
Nuu-chah-nulth Nation - seat: Port Alberni (Nuu-chah-nulth)
Nuxalk Nation - seat: Qʼumqʼuts (Bella Coola) (Nuxalk)
Okanagan Nation Alliance - seat: Westbank (Kelowna) (Syilx)
Quwʼutsun Tribes - seat: Quwʼutsun (Duncan) (Cowichan)
Secwépemc Nation - seat: Tkʼemlúps (Kamloops) (Secwépemc (Shuswap))
shíshálh Nation - seat: chʼatlich (Sechelt) (Sechelt)
Sḵwx̱wú7mesh Úxwumixw - seat: Xwmelchʼstn (North/West Vancouver boundary) (Squamish)
Stlʼatlʼimx Nation - seat: Tʼitʼqʼet (Lillooet) (Stʼatʼimc (Lillooet))
Stsʼailes Nation - seat: Stsʼailes (Stsʼailes (Chehalis))
Stó:lō Nation - seat: Chilliwack (Stó:lō)
šxʷməθkʷəy̓əmaɁɬ təməxʷ - seat: c̓əsnaʔəm (Marpole, Vancouver) (Musqueam)
Tahltan Nation - seat: Telegraph Creek (Tahltan)
Tsilhqotʼin Nation - seat: Ulhkʼatcho (Chilcotin)
Tsʼmsyan Nation - seat: Ganiks Laxha* (Tsimshian)
United Sekani Nations - seat: Kwadacha (Fort Ware) (Sekani)
Utari Mosir - seat: Shana (Ainu)
Wuikinuxv Nation - seat: Rivers Inlet (Wuikinuxv (Owekeeno))
* Ganiks Laxha was called Terrace prior to 1988.
Regional DistrictsBulkley-Nechako Regional District - seat: Burns Lake
Cariboo Regional District - seat: Williams Lake
Cassiar-Stikine Regional District - seat: Cassiar
Central Kootenay Regional District - seat: Nelson
Chilkoot Regional District - seat: Fraser
Columbia-Shuswap Regional District - seat: Salmon Arm
Comox Valley Regional District - seat: Courtenay
Cowichan Valley Regional District - seat: Chemainus
East Kootenay Regional District - seat: Fernie
Fraser Valley Regional District* - seat: ChilliwackFraser-Fort George Regional District - seat: McBride
Greater Cranbrook Regional District - seat: Cranbrook
Greater Kamloops Regional District - seat: Kamloops
Greater Kelowna Regional District - seat: Kelowna
Greater Meziadin Regional District - seat: Meziadin
Greater Nanaimo Regional District - seat: Nanaimo
Greater Prince George Regional District - seat: Prince George
Greater Prince Rupert Regional District - seat: Prince Rupert
Greater Valemount Regional District - seat: Valemount
Greater Vancouver Regional District - seat: Vancouver
Kitimat-Kemano Regional District - seat: Kitimat
Kootenay Boundary Regional District - seat: Trail
National Capital District - seat: Victoria
North Island Regional District - seat: Port McNeill
North Okanagan Regional District - seat: Vernon
Okanagan-Similkameen Regional District - seat: Penticton
Peace River Regional District - seat: Dawson Creek
South Island Regional District - seat: Sooke
Squamish-Lillooet Regional District - seat: Pemberton
Strathcona Regional District - seat: Campbell River
Sunshine Coast Regional District†
- seat: SecheltThompson-Nicola Regional District - seat: Merritt
Tisquit Regional District - seat: Tisquit {RW: Powell River}
* Dissolved 2014; territory split between Nlakaʼpamux Nation, the Sḵwx̱wú7mesh Úxwumixw, the Stlʼatlʼimx Nation, the Stó:lō Nation, and the Stsʼailes Nation IADs.
† Became shíshálh Nation IAD in 2014