Charlie Scott, who can play either in midfield or defence, has joined having been on the books at Vanarama National League North side Altrincham.
Released by Manchester United in the summer of 2018, Scott had earlier had a brief spell in early 2018 on loan at Hamilton Academical in the Scottish Premier, where he made two appearances.
He joined Altrincham in November 2018, having earlier trained with the club.
But his only appearance for the Robins was in a Cheshire Senior Cup tie against Congleton Town where he featured at centre-back.
Also joining Castle is young forward Reinaldo Forbes.
He joins from Total Motion Midland League Division One side Chelmsley Town.
Forbes was originally in the youth system at Kidderminster Harriers and then turned out for Worcester City.