The two males and one female – who cannot be named for legal reasons – were repeatedly attacked at Lord and Lady Polworth Children’s House in Edinburgh.
The girl was even forced to have an abortion when she fell pregnant after the predator raped her.
Samson was later jailed for 14 years after being found guilty of 22 serious sexual offences spanning three decades.
The brave survivors have now raised a civil action against the Kirk and have encouraged others to step forward.
In a statement released by their lawyers Digby Brown Solicitors, the siblings said: “That man was nothing short of evil.
“He robbed us of our childhood, our happiness and our future.
“He might have been jailed but we will never escape the torment of it all and it’s possible we never will.
“There’s no avoiding the memories of what we experienced… even trying to forget the snarl on his face.
“The Church is meant to protect lost and frightened children like we were and they had every chance to protect us yet did nothing.
“We know we weren’t the only ones affected so if there’s anyone else out there then I hope you find the courage to step forward too.”
Samson worked at Lord and Lady Polworth as a superintendent alongside his wife who also worked there as a matron.
His sickening campaign of abuse was carried out between the 1970s and 1990s.
Some victims hid in cupboards or in dog baskets to avoid the abuse.
Yet those who couldn’t escape Samson were subjected to violent attacks – both physical and sexual.
He was jailed for 14 years in 2013 at the High Court in Edinburgh after being found guilty of 22 offences involving sexual abuse and the rape of 12 children.
Eight of these offences happened at the Kirk-run care home with others occurring at different locations across Edinburgh and the Lothians.
Kim Leslie, specialist abuse lawyer and Partner at Digby Brown Solicitors, is leading the civil action against the Kirk.
She said: “Ian Samson was rightly jailed for abuse he inflicted upon children after exploiting his position with the Church of Scotland.
“Now that time limits on historic abuse cases have been lifted we are leading a number of civil actions on behalf of survivors who have bravely stepped forward.
“These claims are being rigorously pursued on the grounds of vicarious liability however it would inappropriate to disclose further details at this time.”