It's possible to add multiple EA's to Azure Cost Management. To achieve this, please follow these steps:
1) Click on settings cog (to the right of the username)
2) Choose Cloud Accounts
3) Click on the main entity to select it and click on "add entity"
4) Follow the instructions in the following tutorial to add the entity
Adding an Entity
*This is just a place holder of the entity, it's not forcing you to host accounts or subscriptions there.
5) Add a second EA in this new entity you just created.
6) If you want to add more EAs, simply add more entities. Once the accounts and subscriptions are auto-
discovered (about 24 hrs) you can then drag and drop them wherever you wish in the entity tree, they
don't have to stay near the EA.