Queen of the South have signed striker Stephen Dobbie from St Johnstone and defender Jamie McQuilken from First Division rivals Gretna.
But midfielder Steve Tosh has been unable to negotiate his release from Gretna, despite having agreed terms with their local rivals.
The 24-year-old Dobbie has signed an 18-month contract.
Dobbie played for Rangers and Hibernian but was farmed out on loan to Third Division Dumbarton, scoring 11 times.
St Johnstone manager Owen Coyle told his club website: "Stephen realised that he is down the pecking order here and asked me that if someone came in for him that he be allowed to move on."
Veteran midfielder Darren Sheridan has also been released by the Perth club.
Dobbie and McQuilken made their debuts for Queens in Saturday's Scottish tie away to Dundee.
The 32-year-old McQuilken has signed a one-and-a-half-year contract.
McCall made the double move for midfielder Tosh and defender McQuilken in an attempt to lift the Dumfries outfit off the bottom of Division One.
Both players worked under McCall when he was previously manager of Falkirk.
Meanwhile, McCall is also hoping to sign St Mirren goalkeeper Craig Hinchcliffe on a pre-contract agreement for next season.
It follows a failed attempt to extend the 34-year-old's loan spell.
Hinchliffe, who has been with St Mirren since 2003, was on the losing side just once in his five appearances for struggling Queens.