Okay, I got it. How to use Mildred. (no, using bloeslava doesn't work as she only gets rid of depression, not anger/hate)
Mildred uses magic to make people's brains explode and to conjure food/water. So pick another partner that doesnt have a brain and doesn't need to eat/drink, and Mildred cant harm or threaten that character.... she's useless. So, take Archie or Bones. Archie is the better choice cause he can build you a shelter. Then again, Bones will be more likely to do your bidding all the time and keep her in check.
If Mildred gives you shit, you have Archie give her shit right back. Archie cant physically fight, but that doesn't mean he's a pacifist. Bones is trickier, but she and Archie can at the very least, physically prevent her from entering your shelter. Mildred cant use her powers against him, and she's denied a safe, sheltered place to sleep at yours and archie's/bones' whim. She'll be forced to cooperate with you regardless of how much she doesn't like you. As long as Archie is on your side or if you have Bones, you have power over her.
If you got Archie, enjoy your free permanent shelter, and free, infinite food and water. Bitchin'