In an interview, the show's chief confirmed that the new arrival will descend on Weatherfield in early 2011 - and is likely to cause some trouble for Roy and Hayley, played by David Neilson and Julie Hesmondhalgh.
Speaking to Inside Soap, Collinson explained: "Early next year we might well bring in a relative of Roy - but I don't want to reveal more than that right now."
He added: "It'll be someone who will really put the cat among the pigeons for him and Hayley, though."
Offering more teasers on what is to come for the Weatherfield soap, Collinson also named builder Owen Armstrong (Ian Puleston-Davies) as one to watch in the coming months.
"Owen's an alpha male who likes to have his own way, although at the same time, he's struggled a lot and loves his children," he said. "We're still learning about him. He can be dark and dangerous, but he'll fight for his kids. Watch this space for Owen!"
Collinson is currently busy working on the soap's 50th anniversary episodes, which will air in December.