Harlequins full-back Ross Chisholm, back row forward James Chisholm and lock George Merrick have all signed new contracts until the summer of 2017.
Ross Chisholm, 24, has made 46 appearances for the Premiership club since making his debut in 2009.
His brother James, 19, is currently in the club's academy but has featured seven times for the first team.
Former England Under-20 international Merrick, 22, joined Quins in 2011 and has played 17 senior games.
"We are really pleased to have secured George, Ross and James here for a further two years," Harlequins academy manager Tony Diprose said.
"All three players are incredibly exciting young talents and I am looking forward to seeing how they develop in the coming years."