Sisters Island Group is an unofficial name applied to a group of three islands off the north end of Flinders Island

Flinders Island, Tasmania

Flinders Island is an island in Bass Strait. It is from Cape Portland, the north-eastern tip of Tasmania, Australia and is the largest island in the Furneaux Group.-History:...

 in the Furneaux Group

Furneaux Group, Tasmania

The Furneaux Group is a group of 52 islands, at the eastern end of Bass Strait, between Victoria and Tasmania, Australia. The islands were named, after British...

 off the north-east coast of Tasmania

Tasmania

Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...

. The Sisters Island group consists of:

• Inner Sister Island
  Inner Sister Island
  Inner Sister Island is an island, with an area of 748 ha, in south-eastern Australia. It is part of Tasmania’s Sisters Island Group, lying in eastern Bass Strait off the northern point of Flinders Island in the Furneaux Group...
  
   (39°41′42"S 147°55′1"E)
• Outer Sister Island
  Outer Sister Island
  Outer Sister Island is a granite and dolerite island, with an area of 545 ha, in south-eastern Australia. It is part of Tasmania’s Sisters Island Group, lying in eastern Bass Strait off the northern point of Flinders Island in the Furneaux Group...
  
   (39°39′14"S 147°59′31"E)
• Shag Reef
  Shag Reef
  Shag Reef is a small granite island, with an area of 1.24 ha, in south-eastern Australia. It is part of Tasmania’s Sisters Island Group, lying in eastern Bass Strait off the northern point of Flinders Island in the Furneaux Group...
  
   (39°40′19"S 147°59′42"E)

The term does not appear in Australian place names at Geoscience Australia

Geoscience Australia

Geoscience Australia is an agency of the Australian federal government. It carries out geoscientific research.On a user pays basis it produces geospatial products such as topographic maps and satellite imagery.-History:...

. The name Sister Islands Conservation Area does appear there and is an official name for the area.