I got a couple question regarding this. Under the account you want to link other accounts to, click on “Members” (under “Followers” on the right hand side). Type in the email of the tumblr account in which you would also like to have access to. It will send you an email (make sure to log into your tumblr account that’s connected to that email address), click on the link and you’ll gain access!
I just realized I could link different accounts to this tumblr, soooo I linked my new(ish) account to here, so expect more postings from me!