Group audits are FREQUENTLY examined in the AAA exam in a variety of ways across many syllabus areas. Candidates are expected to have strong knowledge of the underlying accounting issues and audit implications arising in a group context.
This article https://www.accaglobal.com/gb/en/student/exam-support-resources/professional-exams-study-resources/p7/technical-articles/group-audits.html includes invaluable points of "Exam focus" and is a must read for all students preparing for the exam.