The trio have all agreed to extend their current deals for two years.
Second-rower Ryan, 23, has burst on to the scene this year while Sio, 21, and 24-year-old Paulo are established first graders.
“Matt, Ken and Joseph have all been great finds for the Club and they’ve shown their potential in what has been a tough start to the season for the team,” coach Stephen Kearney told the club website.
“They’re three young guys who are great team members and will play a big part in taking this Club forward, so it’s very pleasing to see them all re-commit.”
He added: “We’ve given those four young lads and others in the Toyota Cup side the challenge of playing in a higher grade and they’ve done very well,” Kearney said.
“Their selection is great reward for the hard work they’ve put in and, for us, it’s all about developing their football and physical condition to a level where they’ll be able to contribute for us in the NRL in the future.”