There's a misconception, which I seem to have helped start, that we will be able to transfer toons between accounts. There's nothing Mythic have said and nothing currently in the account management pages that would facilitate this. So it looks highly unlikely.
The deal is this. Mythic have moved all old EU accounts under their control. There will be new "EU" servers operated by Mythic for French and German customers. However UK players with Prydwen and Excalibur characters will have the option to transfer their toons to Ywain. BUT ... we will only be able to play them on Ywain if our old EU account is paid for and active. So for example, if you want to have both Brighy your Vamp and Brigheiss your old Warden both active, you'd have to pay for both accounts.
There's no news on any account mergers, Mythic deflected my questions on this so it looks unlikely to happen.
Apparently the new EU servers have been up and running and now down again for maintenance. But I've not seen any details on how to access them. They don't appear in the server list via the US client, so I can only assume you have to run the EU client to see them, but the patcher for that seems down.