The stars are due to launch a series of gigs in November (13) to commemorate the band's 20th anniversary, and they were planning to include images of Gately in the show to mark his contribution.
However, bandmember Shane Lynch has now revealed they are locked in a dispute with Gately's estate over the idea.
Lynch tells Britain's The Sun newspaper, "This tour is 100 per cent a celebration of our relationship with Stephen - it's meant to be a party for us guys where we can remember him. We can never leave our Steo (Gately) out. But unfortunately for us guys, you have Stephen's estate in the background and it's very difficult to take his image onboard.
"Even though he was part of Boyzone, I don't know to what extent we can involve him in the show. The estate has their say and sometimes it's a bit difficult to come to a compromise of what we can and can't use... Some people have different ideas of what's right and what's wrong. I don't want to pinpoint any individual - I just call it the estate."
The band was previously banned from using Gately's vocals on their upcoming album, which will reportedly be released to coincide with the tour.
Gately was just 33 years old when he died from an undetected heart condition in 2009.