Maree Mavis Crabtree already faces a string of charges including two counts of murder over the death of her daughter Erin, 18, in 2012, and son Jonathan, 26, in 2017.

The new charge against Crabtree, 53, is over the alleged attempted murder of Jonathan at a Gold Coast property in Maudsland on January 10, 2017.

Jonathon's dead body was found at a home in the nearby suburb of Coomera six months later.

Erin was found dead at the Maudsland home in September 2012.

Both siblings had disabilities. Police have said previously they died as a result of being forced to take prescription medication.

Crabtree was arrested in January 2018.

She is also charged with the grievous bodily harm and torture of a woman, aged in her 20s, and several fraud offences.

Police said at the time the woman had been abused over several years.

Crabtree did not appear in Brisbane Magistrates Court when her charges were mentioned on Monday.

She is remanded in custody, with all charges expected to be mentioned on March 9.

Australian Associated Press