PJ Crossan (Celtic), Ruaridh Langan (Falkirk), Mati Zata (Dundee United) and Rico Quitongo (Hearts) have all put pen to paper with the League 1 side.
Dumbarton had already brought in Stefan McCluskey (Pollok Juniors), Morgyn Neill (Stenhousemuir), Jordan Pettigrew (Livingston), Conor Scullion (Cumbernauld United), Ryan Tierney (Edusport), Isaac Layne (Stranraer), Jordan McMillan (Edusport) and Lewis Crawford (Petershill).
