I don't know what the add-on is called or where I did find it, but I seem to have lost it now.

But if there is someone who knows it or knows the name only, it would help -alot-

The add-on lets you see selected targets target (as in if you have targeted a mob, you will see a small target icon under it's, showing whom it is attacking etc.)

...hope that is enough to tell what I am looking for

thank you for your aid

I think the feature you're looking for is built in in WoW's default interface, check under game options in WoW. I have it activated, but can't remember what the setting is called. And I'm too lazy to check. (:

The Target of Target function is inplemented in blizzard default UI, but in most unit/fram addon an modified Targets Target frame appear.

Get a mod called X-Pearl UnitFrames.

X-perl, Classic Perl and AG UF are all good choices for unite frames that support ToT.