Jackson, who joined the Glasgow Warriors Academy ahead of the 2024/25 season from the Hollywoodbets Sharks U21s. Jackson has been playing with the Great Britain Sevens squad.
He is joined by Gregor Johnston and Murray Waugh, both members of the Glasgow National Talent Pathway.
The Thistles open their campaign against Musselburgh on Saturday morning.
Scottish Thistles Squad for 2026 Melrose Sevens
Fin Callaghan (Scotland 7s) - CAPTAIN
Brent Jackson (Glasgow Warriors Academy)
Lewis Wells (Edinburgh Rugby Academy)
Sam Leweni (Edinburgh Rugby Academy)
Isaac Coates (Edinburgh Rugby Academy)
Mitchell Newell (Strathclyde University)
Gregor Johnston (Glasgow National Talent Pathway 3)
Murray Waugh (Glasgow National Talent Pathway 2)
Ritchie Mitchell (Gala RFC)
Stevie Hamilton (Peebles RFC)
Leo Munro (Stewarts Melville College / Watsonians RFC)
Freddie Owsley (Chinnor RFC)