Earlier this year, show bosses announced that they had cast Holborow as Harley Canning, the teenage cousin of Milligan's character Kyle.
Harley arrives in Erinsborough on Australian screens next week, and Kyle soon realises that he has a tough task ahead as he attempts to tame his wayward relative.
Holborow told TV Week of working with Milligan: "Chris is a really good bloke. We do a lot of angry scenes towards each other, and they're really fun because we both get riled up.
"The relationship on the show is like Kyle is Harley's big brother, and that does transcend into real life."
Holborow also confirmed that Harley will find a girlfriend on Ramsay Street.
The actor said: "He does get into a bit of romance with Rani that makes him want to stay in Ramsay Street. This girl has changed his life, but it's complicated."
Harley, who is expected to be on screen for four months, makes his debut on UK screens on October 1.