Former Wales U20 prop Ben Leung has joined the Quins after a season playing in Federal 1 in France for Bergerac.
The 25-year-old, 120kg tighthead played for Llaneli, the Scarlets and Cardiff before crossing the Channel.
His Scarlets debut came in a front row that included current Welsh caps Ryan Elias and Wyn Jones back in 2014.
He went to the Junior World Championships in France that year when Nicky Smith and Elliot Dee were in the Welsh front row.
Loose head prop Evans is the younger brother of Scarlets and Wales prop Rob Evans.
The 24-year-old is joining Quins from Bridgend and will be looking to quickly surpass the 34 league appearances for made for the Quins in the Premiership by his brother.
Behind the scrum the Quins will be welcoming back flying wing Morgan Griffiths after a season with Cardiff.
Griffiths scored 28 tries in 84 appearances in Carmarthen colours between 2013-18 and has also played for Cardiff Blues A and the Scarlets Premiership Select XV.
