Originally Posted by fluffygrrl

I don't think we understand each other.

A has a wordpress blog, which contains post P.
B also has a wordpress blog, which, in post Q, makes a reference, by url, to post P.

By the nature of the wordpress software, A is sent a trackback, which appears for approval in his comment tab.

A already has a relevant, one way incoming link.

Now, on SEO considerations alone would A be better of by allowing the comment, and consequently linking back to B's post, thus accomplishing a reciprocal linking, or disallowing the comment, and keeping the link one way.