The 20-year old twins, who both debuted in Round 1 this season and remain eligible to play in the Under 20s competition, were signed until the end of season 2017.
This week the Saifiti brothers signed for an additional year, keeping them at the club until at least the end of the 2018 season.
"Daniel and Jacob have been in our system for some time now and we are delighted to secure them at the Club long term," coach Nathan Brown said.
"They have both impressed this year and we know they will only continue to improve.
