You actually seem to get along with Heather still, when you two can put aside work. She did show up to Rex's funeral to show her respect and sympathy.
I know you're very busy, but would it kill you to invite her to lunch some time? Maybe it's impossible to have a non-work conversation, but think how much it would burn Altman if you two became friends and she complained about him in front of the cameras. You know you would love that!! Plus, what's the worst thing that could happen? You two don't talk - aka, the status quo.