You don't add the account to your existing HIVE account. It is its own HIVE account. All you need to do is go to Splinterlands and input the info I gave you and you will be logged in to Splinterlands. The same is true if you want to log into any HIVE app including Hive.Blog. I would recommend changing the master key (password) but that is up to you. I read and responded to your latest message on discord. I'll check back in some hours to see if you got the HIVE/Splinterland account up and running.