Forward Dani Lopez and defender Bondz N'Gala have both joined on loan from Stevenage on initial one-month deals, while Belgian defender Chiro N'Toko has been offered a contract until the end of the campaign.
Lopez joined Boro at the start of the season after arriving from Spain but failed to break into the side and spent three months at Aldershot, where he scored six goals in 12 appearances.
N'Gala, another summer signing for Gary Smith's League One side, has played 19 times but has not featured since a 2-1 defeat to Doncaster in January.
He began his career at West Ham, where he made one League Cup appearance before joining Plymouth Argyle and then moving on to Yeovil.
N'Toko, who was born in the Democratic Republic of Congo, made 14 appearances for Dutch side Den Haag last season.
Meanwhile, Harry Crawford has returned to Dartford on a one-month loan.
The striker joined from the Blue Square Bet Premier side in January, but has been allowed to return for first-team football following the arrivals of Lopez and Craig Beattie at Underhill.