I completed heartache by the number for Cass using the peaceful solution which involves not killing the Van Graffs, then later on I realized I still had Birds of a Feather active in my quest long and went to deliver whatever it is to the strange man. The problem was when I traveled to the Silver Rush from Freeside to report to Gloria about the delievery, the Van Graffs and their guards starting attacking me which caused the quest to fail. At first I assumed it was because I had Cass in my party since I heard from other people that they want her dead, but even after I dismissed her the Graffs are still hostile.

I read on the Wiki that a patch made it impossible to complete both quests on the same playthrough. Has anyone actually found a way around it even if it requires mods? I mean they certainly shouldn't be hostile when they don't even know what I've done which doesn't make much sense.