Be aware that you can only connect one profile/account per music service on Soundiiz at a time. For example, you can only connect one Spotify account to your Soundiiz account to manage it with the Soundiiz interface.
However, we are allowing you to connect up to 6 different profiles/accounts per music service if you need to move your "family plan" you could have on one music service to another. And only for this specific case. Remember that Soundiiz is only for personal usage, and you shouldn't share your Soundiiz account.
You will have to connect each profile separately, transfer to the destination service, disconnect it from Soundiiz, and connect another one.