The A-League's newest club have again added to their inaugural squad, bolstering their goalkeeping depth, defence and midfield
All three had been on trial at the new A-League club, with their arrival swelling the Wanderers' squad to 12 ahead of their debut campaign.
"These boys have all earned the right to be part of the squad and it's great to have them officially on board," Popovic said. "They all have a different past and worked hard to get here but it's great to have them officially part of the squad.
"All three have been trialling for a number of weeks and will play a key role for us in our first season."
Tyson joins after spending three seasons at now-defunct outfit Gold Coast United, having impressed in the club's final A-League season.
The 22-year-old just failed to win a contract at the Sydney FC when he trialed with the Wanderers' city rivals in June, and will compete with veteran Ante Covic for the No.1 jersey at his new club.
Former Blacktown City youth Caira, 19, joins his first A-League club after two seasons in the youth team at English Premier League outfit Aston Villa. Capable of playing both in defence and in midfield, he was part of Australia's Under-20 squad that took part in the 2013 AFC Under-22 Cup qualifying earlier in July.
Trifiro returns to his home city after two seasons in the Victorian Premier League, first with Northcote City and then South Melbourne. The creative midfielder, 24, had been among the most impressive triallists in the Wanderers' first two pre-season fixtures.