If a business is a member of 2 or more groups, the members of all of the groups together are considered to be one large group for payroll tax purposes.
Example
Orange Pty Ltd and Black Pty Ltd are grouped. Orange Pty Ltd is also grouped with Purple Pty Ltd and separately grouped with Green Pty Ltd. Instead of three smaller groups, Orange Pty Ltd, Black Pty Ltd, Purple Pty Ltd and Green Pty Ltd all form one large group.