Digitalisation of the health sector is being adopted by many countries to deliver reliable healthcare services. In healthcare organisations, frauds are rampant possessing a serious threat to good governance. To control such malpractices we present the design of a system for group authorization in healthcare organisations. In this medical professionals are provided with some shares of a secret. To authorise any medical document at least threshold number of medical professionals have to offer their signatures shares. Only when enough number of valid signature shares get combined, the document gets authorised. Maintaining audit logs using the group signature can ensure non-repudiation. We implement threshold Gap Diffie-Hellman (GDH) signature scheme based on the concept of secret sharing for the proposed system. Also, we compare the results of our implementation with the basic RSA scheme. Our implementation has shorter key generation time as compared to a serial RSA scheme. Also, unlike RSA scheme supports the very idea of threshold signatures. Incorporating proposed group authorization system can prevent frauds and corruption in the healthcare sector by providing transparency and accountability.