My main blog on Tumblr is
username.tumblr.com. I follow people, browse the dashboard, and heart posts from that username.
When I post things to a sub-tumblr called
subtumblr.tumblr.com, on that tumblr's 'dashboard' thingy - that is,
tumblr.com/blog/subtumblr - posts have my
username avatar next to them. Posts on my regular dashboard, and
subtumblr's followers' dashboards, have the
subtumblr avatar next to them, and link to the subtumblr, unless I check this box:
This is on the individual sub-tumblr's settings
http://www.tumblr.com/blog/subtumblr/settings or similar.
With that box un-checked, it seems to me that
username will not be revealed to anyone browsing
subtumblr, either on the dashboard or on
subtumblr.tumblr.com. Is this correct? Is there any other area where the name of the parent account might be revealed?