A mother who alleged her 12-year-old daughter had been sexually abused by a staff member at a disability organisation was threatened with legal action for speaking out, a royal commission has heard.

Maree Welch raised suspicions that her daughter Bobbie had been abused by a casual worker at the Family Support Group (FSG) in 1995 but will tell the commission that her complaint was not appropriately handled.

Chief executive of The Disability Trust Margaret Bowen is expected to give evidence. Credit:Lisa Wachsmuth

In the opening address of a public inquiry into disability organisations, the Royal Commission into Institutional Responses to Child Sexual Abuse heard Ms Welch told FSG co-ordinator Melissa Edwards she believed Bobbie may have been raped.

"I hate to tell you this, I think Bobbie has been interfered with, sexually molested or possibly raped – but I don't know whether it has gone as far as rape," the commission heard.