"Practically every day she was being shouted at or being smacked," the girl said in evidence.
She also said she saw her mother throwing one of the baby twins into the cot, causing the baby to cry.
The woman's sister, who lived with the defendant while the alleged offending was taking place, said she saw her slamming one of her daughter's heads into a doorknob.
She also gave evidence about her sister pushing her daughter, who was holding one of the twin babies, down a flight of stairs.
The defendant's brother-in-law told the court that while she fed her children and "actually" looked after them, he also saw her hitting them.
Crown prosecutor Fiona Cleary asked him what he saw happening to the children. He said: "Being abused all the time ... physical, verbal, everything.
"[I] didn't want that happening in my house."
The offending is alleged to have taken place throughout 2014 in Auckland, a Women's Refuge centre in Christchurch and at a home in Ashburton.
The woman moved her children around the country, Ms Cleary said.
Some of the women's 10 children were living with her, while others stayed with grandparents or caregivers.
Some of the children came forward with the allegations after staying with their mother during the holidays and seeing how she was treating their siblings.
The oldest child was 13 at the time while the youngest, twins, were just babies.
The Crown concluded its case yesterday and the trial is expected to finish tomorrow.
