Browse to My Account / Modify Subscription
On this screen you will see a list of Marketplaces available to you and the monthly cost for each*
Select the Marketplace you wish to add by checking the tick box, you will be prompted to enter your log in details for the new marketplace. Enter your marketplace details and click on 'Submit'
Once this is done click on ‘Update’ on the top right hand side of the screen and you will then be registered to use the new Marketplace through SellerExpress. NB if you don't click 'Update', your Marketplace details will not be saved
You will then need to go and add your new account to SellerExpress from the Amazon / Play Settings screens.
*If you are currently a paying customer (not in a trial) payment will be taken straight away for the new account, your monthly bill will also increase.
NB: You need to have opened a new account on the Marketplace in question before it is added to SellerExpress