All in the Family questline got bugged for me. I'll try to go through all the steps to see if it can get sorted through as I'm not sure exactly where it ended up getting messed up.
Went to Bloodmoon Island first and got the Unusual Blade first. Quest log tells me I've found the second half of Anathema. (I'm assuming this is where it becomes bugged)
Went to the graveyard as Malady had updated me that we could move on as the Advocate showed me the way to the next area.
Tarquin was not at the marker indicated on in the Graveyard at this point. Proceeded going around and questing regardless, and ended up getting the Unusual Artefact. Quest line for All in the Family gets updated at this point telling me. "Tarquin will want to know of our success."
When I go to Tarquin on the Vengeance, I have NO dialogue options with him other than trading. Can't complete it now, unless I'm missing something? If I am though the journal tells me of nothing on how to accomplish this.