The teen claimed that his father had beaten him since he was 8.
One of the suspects is believed to be dating the girl in question.
The couple sustained injuries, with the woman's medical expenses amounting to more than S$3,000.
At one point, the man threw the uncle to the ground as a security guard looked on.
The men allegedly felt disrespected by the teens.
The boy was reportedly tied up and beaten in the toilet, where he was kept.
All eight individuals involved in the assault have been arrested.
The mother initially asked the court to sentence her to death, but later requested a lighter sentence.
4 police cars responded to the scene.
The local police said they had nabbed six minors involved in a case of false imprisonment.