The court heard that the attack had its roots in a feud between the TN1 (Trust No-One) gang from the Tulse Hill area of south London and Brixton-based GAS (Guns and Shanks).
Idiabeta and Okusanya were members of the TN1 group out to avenge one of their number who had been stabbed in a bus garage attack carried out by the GAS gang earlier in the day.
Kwame's father Kwaku, a sports journalist, told the court in a statement that his son was full of potential.
He was in the sixth form of Forest Hill School and excelled in sport, music and acting and was ambitious.
Mr Ofosu-Asare said: "Kwame was a very vibrant, energetic and enthusiastic boy.
"His brother and sister are struggling to cope with his death. All our lives have been ruined."
More top news
Teenage twin brothers were found guilty today of murdering a 'quiet, humble' father who dared to intervene in a robbery in north London.
The women were reportedly both students at City and Islington College campus in Holloway Road.
A growing number of ice skating rinks are popping up around London. And in winter, chances are you're not far from one.