Niagara police believe one of the pair was the person who pointed a firearm at a driver and demanded they vacate their vehicle in a July incident on Welland Avenue near Bunting Road.
The accused fled in the car and was believed to have picked up a second teen in the process. The car was recovered not long after the incident.
Those two suspects are also being connected with a stabbing at Pearson Park on Niagara Street on Aug. 17.
Investigators say the victim suffered serious injuries and had to be taken to hospital.
Police says he knew his alleged attackers.
A 17-year-old youth from St. Catharines is facing a total of eight charges, including assault with a weapon and pointing a fire arm, in connection with both occurrences.
The other youth, 16, also from the city is facing three charged including robbery with a firearm and aggravated assault.