Unfortunatlely this approach does not work. Yesterday I tried this with a friend: I sent him my custom presets and he copied them to his custom weather folder. While the presets were available on his side for single player flying, they were still gone as soon as we were in a group.
Maybe someone has another idea how to make it work?
Not to have this option is really a problem, as live weather has the lighnting problem, and the standard presets are just boring. And the biggest problem: They are always set to 15°C at MSL, which results in unrealistic icing in tropical regions (for example Nepal or Papua…)