A forklift driver had to have his hand partially amputated after being attacked with a machete.
Brian Brook and Josh McIntyre pounced on Christopher Mellon and Donna Galloway at a house in Paisley, Renfrewshire.
They also assaulted a three-year-old boy with machetes last September.
Mr Mellon underwent a 22-hour operation to re-attach his finger and his left hand.
At the High Court in Glasgow, Brook and McIntyre, both 26, were found guilty of trying to murder Mr Mellon, 27, while assaulting Ms Galloway, 34.
They were remanded in custody pending sentencing next month in Edinburgh.
After the verdict, a woman, thought to be a relative of one of the pair, yelled at jurors: “I hope you can sleep at night.”
Ms Galloway recalled how the pair and a mystery accomplice were masked and wearing white forensic suits when they stormed in.
She begged them to stop but told jurors: “I just remember a laugh or like ‘yes’. I turned and all three of them were all round Chris.”
The attackers eventually fled leaving the victims badly hurt and the living room covered in blood.
Prosecutor Craig Findlater asked Mr Mellon, who also suffered a fractured skull, how his life had been affected.
Mr Mellon said: “I can’t hold my sons’ hands crossing the road. I don’t have full movement or control in my hands.
“I am going to lose my job. My employers are terminating my contract.”
Lord Brodie deferred sentencing for reports.