Donna raised Cathy since age 13, and was used to being in charge. She watched the children while Cathy and Steve worked, but didn't put any structure or discipline in place for the children. She felt kids should just be allowed to be kids. She would also spoil and baby them, and take the girls' side against Cathy's. Yet she also got very frustrated when the children would not behave.
She and Cathy often disagreed about how to raise the children, and Donna would threaten to stop watching the kids if Cathy didn't like how she did things.
She would also do things to undermine Cathy's authority, such as letting the children call her Mommy. At one point, one of the children was nagging for a cookie. When Cathy said Donna should not give a cookie, Donna did give the cookie because it was better than putting up with the nagging.
When Jo came, Donna was upset about it. She often disagreed with Jo's techniques and was reluctant to change.