Sinclair has been a regular for Hawks this season despite signing professional terms for Warriors. The three players join fellow Warrior, Cameron Blades at Old Anniesland. Hawks have also drafted Alasdair Davidson, the ex Boroughmuir lock now with Borders Rugby.
Clubs will be able to field pro players in the Integrated Tournament that runs in tandem with the Six Nations. Two other Glasgow players have already been involved in the process. Tommy Hayes will be playing with Aberdeen GSFP while Joe Naufahu will join Stirling County.