I heard this a few days ago in a conference call.

Problem:
The adverb “back” in “relate it back” is redundant.

Explanation:
A man promised on the conference call to send some information to a woman who also was on the conference call.

In turn, the woman on the call began a sentence with “I’ll relate it back to …” so as to indicate that she would take the information — the “it” in the sentence — and connect it to something else.

The “re” in “relate” means back.

Therefore, one could argue that “relating back” would never establish the connection.

I believe that the growing tendency, at least in American English, to add words such as “back” after many verbs reflects a growing ignorance about the meanings of the roots of English words.

Solution:
“I’ll relate it to …”