A 16-year-old boy and a 17-year-old boy were both charged on Thursday, 2 September.
They are both due to appear at Highbury Corner Magistrates Court on Thursday, 2 September.
A murder investigation was launched on Tuesday, 10 August after Stelios died in hospital. He had been found with stab wounds inside Lordship Recreation Ground at around 14:15hrs on Sunday, 1 August.