A Group Works Council also called a Combine Works Council (German: Konzernbetriebsrat; KBR) can optionally be established by any Central Works Council belonging to the corporate group headquartered in Germany according to BetrVG § 54(1).
If two or more Central Works Councils exist within the same corporate group that is headquartered in Germany, a Group Works Council can optionally be formed.
This is contrasts with Central Works Councils, which are mandatory to establish.
The size of the Central Works Council can optionally deviate through a Group Works Agreement and or collective agreement per BetrVG § 3.
[1]: 28 According to BetrVG § 58, the Group Works Council has "original competence" over issues that affect two or more subsidiaries cannot be solved by any individual Central Works Councils.