Gallacher, who joined the Pars on loan at the start of this season, has now officially been deemed surplus to Carrow Road requirements. Having looked like cementing his place following the departure of Robert Green to West Ham, the former Dundee United stopper found himself out of favour when Peter Grant replaced Nigel Worthington.
Lewis has also been on loan, at Morecambe, and has impressed in League Two enough to be included in Stuart Pearce's England under-21 squad.
David Marshall is looking irreplaceable between the Canaries' posts at the moment, however, and Matthew Gilks remains his most experienced back-up.
Lewis is still regarded as one for the future, but a bid of around £400,000 from Darren Ferguson at Peterborough is rumoured to be in the offing, and Glenn Roeder will see the potential to spend the cash on recruiting first team reinforcements to help the club more directly.