The depleted Pilgrims have been boosted by the arrivals of Corby Town defender Brad Gascoigne, Sunderland midfielder Liam Agnew (pictured) and Gambian striker Pasulay Njie.
Gascoigne and Njie have penned non-contract forms, while Agnew has joined the Pilgrims on loan from the Black Cats.
The signings come with six first team regulars ruled out.
Striker Charley Sanders, meanwhile, has penned a contract with United and has immediately joined King's Lynn Town on loan for the remainder of the season.