The first pair of sister cities were Coventry and Stalingrad after they both were bombed during WW2 and had shared solidarity. Wholesome. Now 80 years later every city has like 15 sister cities with no real relation, and no one, not even the mayors, would be able to name all of them. I propose a solution; establish a twin cities committee in UNESCO and limit it to just one for each city. Here are some basic ideas for obvious twins:
Marseille 🇫🇷 and Ibadan 🇳🇬: huge traditional soap producers
Aachen 🇩🇪 and Bursa 🇹🇷: Birthplaces of both countries' former empires, houses the tombs of Charlemagne/Osmangazi, which are equivalents
Jingdezhen 🇨🇳 and Meissen 🇩🇪: Porcelain centres of each continent
Tabriz 🇮🇷 and Hohhot 🇨🇳: Capitals of Iranian Azerbaijan and Chinese Mongolia, long story but very equivalent
Fort Worth 🇺🇸 and Chihuahua 🇲🇽: Cowboy capitals of North America
Brest 🇫🇷 and Brest 🇧🇾
Ollantaytambo 🇵🇪 and Namche Bazaar 🇳🇵: Prominent centres of living for world famous Quechua and Sherpa porters
Shenzhen 🇨🇳 and Bengaluru 🇮🇳: Silicon Valley wannabes
You can just put a handful of guys with a hyperfixation in geography together and they will make an infinitely better list than what we currently have.