@WeiWei so from what i understood you must first comply with some EU policies before you are able to add your products to the EU server. I hope its “only” this (even though as a programmer/analyst my self i know its not something simple at all)
@PrimeTeDeV Telling someone about not speaking “proper English” its not cool at all…
you see, not everyone has English as his native language. At least many of us speak English even if we make many mistakes, do you speak proper Greek like me? The fact that we all speak English here is so that we can understand each other but noone is obligated to speak English fluently. What is really ironic (there… you know a few Greek words after all) is that you say that in a Chinese forum. We are more than 7 billion people and not everything and everyone revolves around you guys. Better think before you speak or as we say here in Greece “dip your tongue in your mind/brain first”.
Anyway what you say after that unfortunate first sentence, is correct. Its another thing to connect two databases and another thing to replicate or migrate data between them. You can have the same login but having the same data is totally diffferent. If from the beggining the goal is to have the same data between all servers then you could have replication between them but if the goal is to have different servers with diferent products/settings/policies etc (like in our case) then a few lines of code wouldnt do the trick.
What you could have (but even then you should be careful for security issues as Weiwei said) is an api to give the user the ability to migrate some of his settings/products from one server to another having in mind that you should check for already existing devices etc and handle that.
For example i am at locale “MainLand China” and i change it to “Europe”, i could have an option to replicate my products to the new server (not having to connect everything again) but what would happen if a product is not available to this new server yet? It would have to be something pretty complicated to work well, like
“I want to change server”, “here are your sensors etc that can be migrated to the new server, do you want to migrate them?” (checkboxes) etc. And what if you change something in the new server and expect to find it if you revert to the old one? Well, thats a lot of work and a lot of a mess and certainly not a few lines of code… It would be great but what is more important now is to have a couple of servers that has full support from both Xiaomi and Yeelight.
Actually there is no point discussing this on yeelight forum since the migration option should be mostly on the xiaomi side (the many sensors are the problem not the few bubls) and that will never happen 
Lets concentrate to the new European server and to Singapore server and forget about such things as data migration at this time.
What Yeelight could have is an Export / Import feature for custom scenes and customization settings so you could Export them and Import them when you want. This way you could import them after you add your bulb in a new server or even share it with others. That would be way “easier” and more efficient.