Hibernian have bolstered their defence with the loan signings of Owen Bevan and Nectarios Triantis.
Both centre-backs are 20, with Bevan arriving from Bournemouth, while Sunderland's Triantis is reunited with head coach Nick Montgomery.
The Australian won last year's A-League title under Montgomery at Central Coast Mariners.
Late on deadline day, a deal for Sunderland forward Eliezer Mayenda, 18, was also announced.
The Spanish teenager has featured eight times for the English Championship side since moving from French Ligue 2 side Sochaux.
"I signed him for the Mariners and gave him his A-League debut as I saw huge potential in him," said Montgomery of Triantis.