Sentencing submissions are set to continue for Steven Graham Peet following his guilty pleas to murdering his partner and her two children.

Peet is scheduled to appear in the South Australian Supreme Court on Wednesday after victim impact statements earlier this month.

He has admitted to murdering Adeline Yvette Wilson-Rigney and her children Amber, 6, and Korey, 5. at their home north of Adelaide in May 2016.

Peet strangled all three with cable ties but also inflicted serious head injuries on Ms Wilson-Rigney.

In her victim impact statement last week, the children's maternal grandmother Donna Rigney told of her struggles since the tragedy.

"The pain that you have brought upon me and my family has caused overwhelming grief every day," Ms Rigney told Peet.

Defence counsel Bill Boucaut said Peet would feel "shame and regret" for the rest of his life.

Prosecutor Tim Preston said Peet killed Ms Wilson-Rigney in anger and her children because they witnessed their mother's murder.

© AAP 2018