The independent expert commissioned to review Chemist Warehouse’s $30 billion merger with Sigma Healthcare has backed controversial related-party transactions between the chemist giant’s co-founders and their relatives, paving the way for a deal to be completed in February.

Consulting firm Grant Thornton said the arrangements, which will give Chemist Warehouse’s billionaire co-founders Jack and Sam Gance and Mario Verrocchi control over many of the country’s pharmacies, were “fair and reasonable”.