Portadown signed Jamie Marks and Henry McStay before the transfer window closed at midnight on Wednesday.
Former Linfield player Jamie Marks has joined Portadown
Former Linfield midfielder Marks joins on a one-year contract after being put on the transfer list a fortnight ago by Ballymena United.
Republic of Ireland U21 defender McStay was a trainee professional with Leeds United for four years.
The pair are replacements for Kris Lindsay and Cullen Feeney, who left Shamrock Park in the summer.
Marks, like McStay, was a trainee professional with Leeds and played for Hull City before moving to Linfield.
The 28-year-old won two league titles, an Irish Cup, two Co Antrim Shields and three League Cups during a successful spell at Windsor Park.
McStay plumped for the Ports after turning down chances to join Aberdeen, Bohemians or Finn Harps.
The 20-year-old from Co Armagh wanted a move back home as he is due to start a physiotherapy course in Belfast.