Here's a quick list to your questions:
1. Greselda's fountain is a decoration and there is now a cap of deco's. As I wrote in my previous post, you may need to sell a decoration to buy Greselda's fountain. It is a gem purchase item only. Players with multiple fountains, bought them with gems. Here is the
thread which you must do first before you get the option to buy the fountain. The fountain is part of Greselda's Dark Garden goalline.
2. The locket: you have to wait for a
Monster Hunt season and the locket can be purchased with gold troll tokens in the Trade Wagon.
From thread: * The Locket storyline first came about in a goal called Poof and Gone released in September 2013. The storyline ended in limbo, so now we now what happened! The trolls founds it and it's now available for purchase with 5 gold troll tokens. The Ornate Locket, as it ties in to the main story, is also not bound to Monster Hunts.
3. You can switch between games on your device if you know the passwords to each of your accounts. If you DO know your passwords, follow the steps in
this post in the Hub and use the login feature.
If you DO NOT know you password, you can contact Storm8 Support and seek assistance.
4. To see what storyline you're up to, you should look at the Castle Story Outline Guide. This has a list of all main story goals in the order they were released.
click here.