Oh, I really have to disagree with that. They have a joint custody agreement between them, no one is taking the baby away from anyone. Theresa COULD have been looking for a larger place while Tate has been in the hospital, but instead was going to use the place she currently lived inwhich was fine. Also plotting how to get Brady back in her bed. But she proved herself totally inept at making room for the baby there. And people much younger than Theresa, who have never had anything to do with a baby, (whether real life, or on the show) have done a better job in small spaces.
It is called "common sense". Also, caring about the child more than yourself.
As has been stated, he offered her the larger place, servants,money for the care of the baby, and more $$$ for herself. She said NO.
There is no reason they have to live together, in a separate home, to raise Tate. NONE whatsoever.