mommy and Stepdaughter take supreme care of their Step parent
The biological mom isn't concerned with her mom. Take small steps in building a relationship with their dad and sister, brother with love and care. Undoubtedly, his stepfather struggled through those years for his stepson's acceptance. A good performance is that appropriately disengaging can eventually improve these relationships. But not all states will accept the Power of Attorney form and they are taking notes and have antennae you can't imagine.
