Chair lift will have been replaced in December 2025
https://www.lesgets.com/en/rosta/

It looks like the Ski area Mont des Brumes stopped its operations in 2024

http://www.montdesbrumes.be/
https://www.sudinfo.be/id798943/article/2024-02-26/le-mont-des-brumes-lance-un-appel-projet-pour-exploiter-sa-piste-de-ski-la
https://www.lavenir.net/regions/verviers/stoumont/2024/02/26/les-possibilites-sont-larges-les-proprietaires-de-la-piste-de-ski-du-mont-des-brumes-la-plus-raide-de-belgique-veulent-lexploiter-toute-lannee-MRV2GPIPSBBN5KMV4XDNV7QB2I/

This lift will have been replaced come december 2025 by a 6 seater detachable chairlift (Linga Express)
https://www.chatel.com/telesiege-du-linga.html

The TK Cuboré (drag lift) is part of both skipasses Avoriaz and Champéry – Les Crosets – Champoussin – Morgins (and also part of the runs Abricotine and Les Cases); this means the ski resorts area's technically overlap here.
But I don't know how to properly implement this, while having the Portes du Soleil still being a correct multipolygon.

https://www.calameo.com/avoriaz/read/0028278921517ff3fe8dd?page=1

https://www.infosnow.ch/~apgmontagne/?id=183&tab=map-wi&lang=fr

L’Essert – Abondance should be added to le portes du soleil winter sports area as a subarea

Sépaya 1 and 2 are likely the other way around

Portes du soleil winter sports area should here probably be a multipolygon